From fe8ef3f08fc2d76d07c96763f33c6796281c4d0b Mon Sep 17 00:00:00 2001
From: Henry Oswald <henry.oswald@sharelatex.com>
Date: Thu, 16 Jan 2020 13:09:47 +0000
Subject: [PATCH] Merge pull request #2531 from overleaf/ho-restore-lodash-2526

Revert "Reverts move from underscore to lodash"

GitOrigin-RevId: 1ea964d5c98a85f9490c0e731d6a68335df93c67
---
 .../app/src/infrastructure/PackageVersions.js |    4 +-
 .../aceEditor/metadata/MetadataManager.js     |    6 +-
 .../js/ide/metadata/services/metadata.js      |    2 +-
 services/web/frontend/js/libraries.js         |    2 +-
 .../web/frontend/js/main/register-users.js    |    2 +-
 .../web/frontend/js/main/user-membership.js   |    2 +-
 .../js/vendor/libs/underscore-1.9.1.js        | 1692 -----------------
 services/web/webpack.config.js                |   15 +-
 8 files changed, 11 insertions(+), 1714 deletions(-)
 delete mode 100644 services/web/frontend/js/vendor/libs/underscore-1.9.1.js

diff --git a/services/web/app/src/infrastructure/PackageVersions.js b/services/web/app/src/infrastructure/PackageVersions.js
index 5795598114..ef5040ef37 100644
--- a/services/web/app/src/infrastructure/PackageVersions.js
+++ b/services/web/app/src/infrastructure/PackageVersions.js
@@ -7,9 +7,7 @@
  */
 const version = {
   ace: '1.4.5', // Upgrade instructions: https://github.com/overleaf/write_latex/wiki/Upgrading-Ace
-  fineuploader: '5.15.4',
-  // For frontend. Backend has a different version defined in package.json
-  underscore: '1.9.1'
+  fineuploader: '5.15.4'
 }
 
 module.exports = {
diff --git a/services/web/frontend/js/ide/editor/directives/aceEditor/metadata/MetadataManager.js b/services/web/frontend/js/ide/editor/directives/aceEditor/metadata/MetadataManager.js
index e2770cb3ff..83ef98ee46 100644
--- a/services/web/frontend/js/ide/editor/directives/aceEditor/metadata/MetadataManager.js
+++ b/services/web/frontend/js/ide/editor/directives/aceEditor/metadata/MetadataManager.js
@@ -53,13 +53,13 @@ define(['ace/ace'], function() {
         }
         const commandFragment = getLastCommandFragment(lineUpToCursor)
 
-        const linesContainPackage = _.any(change.lines, line =>
+        const linesContainPackage = _.some(change.lines, line =>
           line.match(/^\\usepackage(?:\[.{0,80}?])?{(.{0,80}?)}/)
         )
-        const linesContainReqPackage = _.any(change.lines, line =>
+        const linesContainReqPackage = _.some(change.lines, line =>
           line.match(/^\\RequirePackage(?:\[.{0,80}?])?{(.{0,80}?)}/)
         )
-        const linesContainLabel = _.any(change.lines, line =>
+        const linesContainLabel = _.some(change.lines, line =>
           line.match(/\\label{(.{0,80}?)}/)
         )
         const linesContainMeta =
diff --git a/services/web/frontend/js/ide/metadata/services/metadata.js b/services/web/frontend/js/ide/metadata/services/metadata.js
index a195b8596c..7f229b4232 100644
--- a/services/web/frontend/js/ide/metadata/services/metadata.js
+++ b/services/web/frontend/js/ide/metadata/services/metadata.js
@@ -38,7 +38,7 @@ define(['base'], App =>
     }
 
     metadata.getAllLabels = () =>
-      _.flatten(
+      _.flattenDeep(
         (() => {
           const result = []
           for (let docId in state.documents) {
diff --git a/services/web/frontend/js/libraries.js b/services/web/frontend/js/libraries.js
index 722305e145..cf5465aa7b 100644
--- a/services/web/frontend/js/libraries.js
+++ b/services/web/frontend/js/libraries.js
@@ -2,10 +2,10 @@ define([
   'jquery',
   'angular',
   'angular-sanitize',
+  'lodash',
   'libs/angular-autocomplete/angular-autocomplete',
   'libs/ui-bootstrap',
   'libs/ng-context-menu-0.1.4',
-  'libs/underscore-1.9.1',
   'libs/jquery.storage',
   'libs/angular-cookie',
   'libs/passfield',
diff --git a/services/web/frontend/js/main/register-users.js b/services/web/frontend/js/main/register-users.js
index 7d7ee58789..e50ca7881c 100644
--- a/services/web/frontend/js/main/register-users.js
+++ b/services/web/frontend/js/main/register-users.js
@@ -21,7 +21,7 @@ define(['base'], App =>
       const regexBySpaceOrComma = /[\s,]+/
       let emails = emailsString.split(regexBySpaceOrComma)
       emails = _.map(emails, email => (email = email.trim()))
-      emails = _.select(emails, email => email.indexOf('@') !== -1)
+      emails = _.filter(emails, email => email.indexOf('@') !== -1)
       return emails
     }
 
diff --git a/services/web/frontend/js/main/user-membership.js b/services/web/frontend/js/main/user-membership.js
index 309c1c7116..70e0eef3b8 100644
--- a/services/web/frontend/js/main/user-membership.js
+++ b/services/web/frontend/js/main/user-membership.js
@@ -36,7 +36,7 @@ define(['base'], function(App) {
       const regexBySpaceOrComma = /[\s,]+/
       let emails = emailsString.split(regexBySpaceOrComma)
       emails = _.map(emails, email => (email = email.trim()))
-      emails = _.select(emails, email => email.indexOf('@') !== -1)
+      emails = _.filter(emails, email => email.indexOf('@') !== -1)
       return emails
     }
 
diff --git a/services/web/frontend/js/vendor/libs/underscore-1.9.1.js b/services/web/frontend/js/vendor/libs/underscore-1.9.1.js
deleted file mode 100644
index 8219dc5085..0000000000
--- a/services/web/frontend/js/vendor/libs/underscore-1.9.1.js
+++ /dev/null
@@ -1,1692 +0,0 @@
-//     Underscore.js 1.9.1
-//     http://underscorejs.org
-//     (c) 2009-2018 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
-//     Underscore may be freely distributed under the MIT license.
-
-(function() {
-
-  // Baseline setup
-  // --------------
-
-  // Establish the root object, `window` (`self`) in the browser, `global`
-  // on the server, or `this` in some virtual machines. We use `self`
-  // instead of `window` for `WebWorker` support.
-  var root = typeof self == 'object' && self.self === self && self ||
-            typeof global == 'object' && global.global === global && global ||
-            this ||
-            {};
-
-  // Save the previous value of the `_` variable.
-  var previousUnderscore = root._;
-
-  // Save bytes in the minified (but not gzipped) version:
-  var ArrayProto = Array.prototype, ObjProto = Object.prototype;
-  var SymbolProto = typeof Symbol !== 'undefined' ? Symbol.prototype : null;
-
-  // Create quick reference variables for speed access to core prototypes.
-  var push = ArrayProto.push,
-      slice = ArrayProto.slice,
-      toString = ObjProto.toString,
-      hasOwnProperty = ObjProto.hasOwnProperty;
-
-  // All **ECMAScript 5** native function implementations that we hope to use
-  // are declared here.
-  var nativeIsArray = Array.isArray,
-      nativeKeys = Object.keys,
-      nativeCreate = Object.create;
-
-  // Naked function reference for surrogate-prototype-swapping.
-  var Ctor = function(){};
-
-  // Create a safe reference to the Underscore object for use below.
-  var _ = function(obj) {
-    if (obj instanceof _) return obj;
-    if (!(this instanceof _)) return new _(obj);
-    this._wrapped = obj;
-  };
-
-  // Export the Underscore object for **Node.js**, with
-  // backwards-compatibility for their old module API. If we're in
-  // the browser, add `_` as a global object.
-  // (`nodeType` is checked to ensure that `module`
-  // and `exports` are not HTML elements.)
-  if (typeof exports != 'undefined' && !exports.nodeType) {
-    if (typeof module != 'undefined' && !module.nodeType && module.exports) {
-      exports = module.exports = _;
-    }
-    exports._ = _;
-  } else {
-    root._ = _;
-  }
-
-  // Current version.
-  _.VERSION = '1.9.1';
-
-  // Internal function that returns an efficient (for current engines) version
-  // of the passed-in callback, to be repeatedly applied in other Underscore
-  // functions.
-  var optimizeCb = function(func, context, argCount) {
-    if (context === void 0) return func;
-    switch (argCount == null ? 3 : argCount) {
-      case 1: return function(value) {
-        return func.call(context, value);
-      };
-      // The 2-argument case is omitted because we’re not using it.
-      case 3: return function(value, index, collection) {
-        return func.call(context, value, index, collection);
-      };
-      case 4: return function(accumulator, value, index, collection) {
-        return func.call(context, accumulator, value, index, collection);
-      };
-    }
-    return function() {
-      return func.apply(context, arguments);
-    };
-  };
-
-  var builtinIteratee;
-
-  // An internal function to generate callbacks that can be applied to each
-  // element in a collection, returning the desired result — either `identity`,
-  // an arbitrary callback, a property matcher, or a property accessor.
-  var cb = function(value, context, argCount) {
-    if (_.iteratee !== builtinIteratee) return _.iteratee(value, context);
-    if (value == null) return _.identity;
-    if (_.isFunction(value)) return optimizeCb(value, context, argCount);
-    if (_.isObject(value) && !_.isArray(value)) return _.matcher(value);
-    return _.property(value);
-  };
-
-  // External wrapper for our callback generator. Users may customize
-  // `_.iteratee` if they want additional predicate/iteratee shorthand styles.
-  // This abstraction hides the internal-only argCount argument.
-  _.iteratee = builtinIteratee = function(value, context) {
-    return cb(value, context, Infinity);
-  };
-
-  // Some functions take a variable number of arguments, or a few expected
-  // arguments at the beginning and then a variable number of values to operate
-  // on. This helper accumulates all remaining arguments past the function’s
-  // argument length (or an explicit `startIndex`), into an array that becomes
-  // the last argument. Similar to ES6’s "rest parameter".
-  var restArguments = function(func, startIndex) {
-    startIndex = startIndex == null ? func.length - 1 : +startIndex;
-    return function() {
-      var length = Math.max(arguments.length - startIndex, 0),
-          rest = Array(length),
-          index = 0;
-      for (; index < length; index++) {
-        rest[index] = arguments[index + startIndex];
-      }
-      switch (startIndex) {
-        case 0: return func.call(this, rest);
-        case 1: return func.call(this, arguments[0], rest);
-        case 2: return func.call(this, arguments[0], arguments[1], rest);
-      }
-      var args = Array(startIndex + 1);
-      for (index = 0; index < startIndex; index++) {
-        args[index] = arguments[index];
-      }
-      args[startIndex] = rest;
-      return func.apply(this, args);
-    };
-  };
-
-  // An internal function for creating a new object that inherits from another.
-  var baseCreate = function(prototype) {
-    if (!_.isObject(prototype)) return {};
-    if (nativeCreate) return nativeCreate(prototype);
-    Ctor.prototype = prototype;
-    var result = new Ctor;
-    Ctor.prototype = null;
-    return result;
-  };
-
-  var shallowProperty = function(key) {
-    return function(obj) {
-      return obj == null ? void 0 : obj[key];
-    };
-  };
-
-  var has = function(obj, path) {
-    return obj != null && hasOwnProperty.call(obj, path);
-  }
-
-  var deepGet = function(obj, path) {
-    var length = path.length;
-    for (var i = 0; i < length; i++) {
-      if (obj == null) return void 0;
-      obj = obj[path[i]];
-    }
-    return length ? obj : void 0;
-  };
-
-  // Helper for collection methods to determine whether a collection
-  // should be iterated as an array or as an object.
-  // Related: http://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength
-  // Avoids a very nasty iOS 8 JIT bug on ARM-64. #2094
-  var MAX_ARRAY_INDEX = Math.pow(2, 53) - 1;
-  var getLength = shallowProperty('length');
-  var isArrayLike = function(collection) {
-    var length = getLength(collection);
-    return typeof length == 'number' && length >= 0 && length <= MAX_ARRAY_INDEX;
-  };
-
-  // Collection Functions
-  // --------------------
-
-  // The cornerstone, an `each` implementation, aka `forEach`.
-  // Handles raw objects in addition to array-likes. Treats all
-  // sparse array-likes as if they were dense.
-  _.each = _.forEach = function(obj, iteratee, context) {
-    iteratee = optimizeCb(iteratee, context);
-    var i, length;
-    if (isArrayLike(obj)) {
-      for (i = 0, length = obj.length; i < length; i++) {
-        iteratee(obj[i], i, obj);
-      }
-    } else {
-      var keys = _.keys(obj);
-      for (i = 0, length = keys.length; i < length; i++) {
-        iteratee(obj[keys[i]], keys[i], obj);
-      }
-    }
-    return obj;
-  };
-
-  // Return the results of applying the iteratee to each element.
-  _.map = _.collect = function(obj, iteratee, context) {
-    iteratee = cb(iteratee, context);
-    var keys = !isArrayLike(obj) && _.keys(obj),
-        length = (keys || obj).length,
-        results = Array(length);
-    for (var index = 0; index < length; index++) {
-      var currentKey = keys ? keys[index] : index;
-      results[index] = iteratee(obj[currentKey], currentKey, obj);
-    }
-    return results;
-  };
-
-  // Create a reducing function iterating left or right.
-  var createReduce = function(dir) {
-    // Wrap code that reassigns argument variables in a separate function than
-    // the one that accesses `arguments.length` to avoid a perf hit. (#1991)
-    var reducer = function(obj, iteratee, memo, initial) {
-      var keys = !isArrayLike(obj) && _.keys(obj),
-          length = (keys || obj).length,
-          index = dir > 0 ? 0 : length - 1;
-      if (!initial) {
-        memo = obj[keys ? keys[index] : index];
-        index += dir;
-      }
-      for (; index >= 0 && index < length; index += dir) {
-        var currentKey = keys ? keys[index] : index;
-        memo = iteratee(memo, obj[currentKey], currentKey, obj);
-      }
-      return memo;
-    };
-
-    return function(obj, iteratee, memo, context) {
-      var initial = arguments.length >= 3;
-      return reducer(obj, optimizeCb(iteratee, context, 4), memo, initial);
-    };
-  };
-
-  // **Reduce** builds up a single result from a list of values, aka `inject`,
-  // or `foldl`.
-  _.reduce = _.foldl = _.inject = createReduce(1);
-
-  // The right-associative version of reduce, also known as `foldr`.
-  _.reduceRight = _.foldr = createReduce(-1);
-
-  // Return the first value which passes a truth test. Aliased as `detect`.
-  _.find = _.detect = function(obj, predicate, context) {
-    var keyFinder = isArrayLike(obj) ? _.findIndex : _.findKey;
-    var key = keyFinder(obj, predicate, context);
-    if (key !== void 0 && key !== -1) return obj[key];
-  };
-
-  // Return all the elements that pass a truth test.
-  // Aliased as `select`.
-  _.filter = _.select = function(obj, predicate, context) {
-    var results = [];
-    predicate = cb(predicate, context);
-    _.each(obj, function(value, index, list) {
-      if (predicate(value, index, list)) results.push(value);
-    });
-    return results;
-  };
-
-  // Return all the elements for which a truth test fails.
-  _.reject = function(obj, predicate, context) {
-    return _.filter(obj, _.negate(cb(predicate)), context);
-  };
-
-  // Determine whether all of the elements match a truth test.
-  // Aliased as `all`.
-  _.every = _.all = function(obj, predicate, context) {
-    predicate = cb(predicate, context);
-    var keys = !isArrayLike(obj) && _.keys(obj),
-        length = (keys || obj).length;
-    for (var index = 0; index < length; index++) {
-      var currentKey = keys ? keys[index] : index;
-      if (!predicate(obj[currentKey], currentKey, obj)) return false;
-    }
-    return true;
-  };
-
-  // Determine if at least one element in the object matches a truth test.
-  // Aliased as `any`.
-  _.some = _.any = function(obj, predicate, context) {
-    predicate = cb(predicate, context);
-    var keys = !isArrayLike(obj) && _.keys(obj),
-        length = (keys || obj).length;
-    for (var index = 0; index < length; index++) {
-      var currentKey = keys ? keys[index] : index;
-      if (predicate(obj[currentKey], currentKey, obj)) return true;
-    }
-    return false;
-  };
-
-  // Determine if the array or object contains a given item (using `===`).
-  // Aliased as `includes` and `include`.
-  _.contains = _.includes = _.include = function(obj, item, fromIndex, guard) {
-    if (!isArrayLike(obj)) obj = _.values(obj);
-    if (typeof fromIndex != 'number' || guard) fromIndex = 0;
-    return _.indexOf(obj, item, fromIndex) >= 0;
-  };
-
-  // Invoke a method (with arguments) on every item in a collection.
-  _.invoke = restArguments(function(obj, path, args) {
-    var contextPath, func;
-    if (_.isFunction(path)) {
-      func = path;
-    } else if (_.isArray(path)) {
-      contextPath = path.slice(0, -1);
-      path = path[path.length - 1];
-    }
-    return _.map(obj, function(context) {
-      var method = func;
-      if (!method) {
-        if (contextPath && contextPath.length) {
-          context = deepGet(context, contextPath);
-        }
-        if (context == null) return void 0;
-        method = context[path];
-      }
-      return method == null ? method : method.apply(context, args);
-    });
-  });
-
-  // Convenience version of a common use case of `map`: fetching a property.
-  _.pluck = function(obj, key) {
-    return _.map(obj, _.property(key));
-  };
-
-  // Convenience version of a common use case of `filter`: selecting only objects
-  // containing specific `key:value` pairs.
-  _.where = function(obj, attrs) {
-    return _.filter(obj, _.matcher(attrs));
-  };
-
-  // Convenience version of a common use case of `find`: getting the first object
-  // containing specific `key:value` pairs.
-  _.findWhere = function(obj, attrs) {
-    return _.find(obj, _.matcher(attrs));
-  };
-
-  // Return the maximum element (or element-based computation).
-  _.max = function(obj, iteratee, context) {
-    var result = -Infinity, lastComputed = -Infinity,
-        value, computed;
-    if (iteratee == null || typeof iteratee == 'number' && typeof obj[0] != 'object' && obj != null) {
-      obj = isArrayLike(obj) ? obj : _.values(obj);
-      for (var i = 0, length = obj.length; i < length; i++) {
-        value = obj[i];
-        if (value != null && value > result) {
-          result = value;
-        }
-      }
-    } else {
-      iteratee = cb(iteratee, context);
-      _.each(obj, function(v, index, list) {
-        computed = iteratee(v, index, list);
-        if (computed > lastComputed || computed === -Infinity && result === -Infinity) {
-          result = v;
-          lastComputed = computed;
-        }
-      });
-    }
-    return result;
-  };
-
-  // Return the minimum element (or element-based computation).
-  _.min = function(obj, iteratee, context) {
-    var result = Infinity, lastComputed = Infinity,
-        value, computed;
-    if (iteratee == null || typeof iteratee == 'number' && typeof obj[0] != 'object' && obj != null) {
-      obj = isArrayLike(obj) ? obj : _.values(obj);
-      for (var i = 0, length = obj.length; i < length; i++) {
-        value = obj[i];
-        if (value != null && value < result) {
-          result = value;
-        }
-      }
-    } else {
-      iteratee = cb(iteratee, context);
-      _.each(obj, function(v, index, list) {
-        computed = iteratee(v, index, list);
-        if (computed < lastComputed || computed === Infinity && result === Infinity) {
-          result = v;
-          lastComputed = computed;
-        }
-      });
-    }
-    return result;
-  };
-
-  // Shuffle a collection.
-  _.shuffle = function(obj) {
-    return _.sample(obj, Infinity);
-  };
-
-  // Sample **n** random values from a collection using the modern version of the
-  // [Fisher-Yates shuffle](http://en.wikipedia.org/wiki/Fisher–Yates_shuffle).
-  // If **n** is not specified, returns a single random element.
-  // The internal `guard` argument allows it to work with `map`.
-  _.sample = function(obj, n, guard) {
-    if (n == null || guard) {
-      if (!isArrayLike(obj)) obj = _.values(obj);
-      return obj[_.random(obj.length - 1)];
-    }
-    var sample = isArrayLike(obj) ? _.clone(obj) : _.values(obj);
-    var length = getLength(sample);
-    n = Math.max(Math.min(n, length), 0);
-    var last = length - 1;
-    for (var index = 0; index < n; index++) {
-      var rand = _.random(index, last);
-      var temp = sample[index];
-      sample[index] = sample[rand];
-      sample[rand] = temp;
-    }
-    return sample.slice(0, n);
-  };
-
-  // Sort the object's values by a criterion produced by an iteratee.
-  _.sortBy = function(obj, iteratee, context) {
-    var index = 0;
-    iteratee = cb(iteratee, context);
-    return _.pluck(_.map(obj, function(value, key, list) {
-      return {
-        value: value,
-        index: index++,
-        criteria: iteratee(value, key, list)
-      };
-    }).sort(function(left, right) {
-      var a = left.criteria;
-      var b = right.criteria;
-      if (a !== b) {
-        if (a > b || a === void 0) return 1;
-        if (a < b || b === void 0) return -1;
-      }
-      return left.index - right.index;
-    }), 'value');
-  };
-
-  // An internal function used for aggregate "group by" operations.
-  var group = function(behavior, partition) {
-    return function(obj, iteratee, context) {
-      var result = partition ? [[], []] : {};
-      iteratee = cb(iteratee, context);
-      _.each(obj, function(value, index) {
-        var key = iteratee(value, index, obj);
-        behavior(result, value, key);
-      });
-      return result;
-    };
-  };
-
-  // Groups the object's values by a criterion. Pass either a string attribute
-  // to group by, or a function that returns the criterion.
-  _.groupBy = group(function(result, value, key) {
-    if (has(result, key)) result[key].push(value); else result[key] = [value];
-  });
-
-  // Indexes the object's values by a criterion, similar to `groupBy`, but for
-  // when you know that your index values will be unique.
-  _.indexBy = group(function(result, value, key) {
-    result[key] = value;
-  });
-
-  // Counts instances of an object that group by a certain criterion. Pass
-  // either a string attribute to count by, or a function that returns the
-  // criterion.
-  _.countBy = group(function(result, value, key) {
-    if (has(result, key)) result[key]++; else result[key] = 1;
-  });
-
-  var reStrSymbol = /[^\ud800-\udfff]|[\ud800-\udbff][\udc00-\udfff]|[\ud800-\udfff]/g;
-  // Safely create a real, live array from anything iterable.
-  _.toArray = function(obj) {
-    if (!obj) return [];
-    if (_.isArray(obj)) return slice.call(obj);
-    if (_.isString(obj)) {
-      // Keep surrogate pair characters together
-      return obj.match(reStrSymbol);
-    }
-    if (isArrayLike(obj)) return _.map(obj, _.identity);
-    return _.values(obj);
-  };
-
-  // Return the number of elements in an object.
-  _.size = function(obj) {
-    if (obj == null) return 0;
-    return isArrayLike(obj) ? obj.length : _.keys(obj).length;
-  };
-
-  // Split a collection into two arrays: one whose elements all satisfy the given
-  // predicate, and one whose elements all do not satisfy the predicate.
-  _.partition = group(function(result, value, pass) {
-    result[pass ? 0 : 1].push(value);
-  }, true);
-
-  // Array Functions
-  // ---------------
-
-  // Get the first element of an array. Passing **n** will return the first N
-  // values in the array. Aliased as `head` and `take`. The **guard** check
-  // allows it to work with `_.map`.
-  _.first = _.head = _.take = function(array, n, guard) {
-    if (array == null || array.length < 1) return n == null ? void 0 : [];
-    if (n == null || guard) return array[0];
-    return _.initial(array, array.length - n);
-  };
-
-  // Returns everything but the last entry of the array. Especially useful on
-  // the arguments object. Passing **n** will return all the values in
-  // the array, excluding the last N.
-  _.initial = function(array, n, guard) {
-    return slice.call(array, 0, Math.max(0, array.length - (n == null || guard ? 1 : n)));
-  };
-
-  // Get the last element of an array. Passing **n** will return the last N
-  // values in the array.
-  _.last = function(array, n, guard) {
-    if (array == null || array.length < 1) return n == null ? void 0 : [];
-    if (n == null || guard) return array[array.length - 1];
-    return _.rest(array, Math.max(0, array.length - n));
-  };
-
-  // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.
-  // Especially useful on the arguments object. Passing an **n** will return
-  // the rest N values in the array.
-  _.rest = _.tail = _.drop = function(array, n, guard) {
-    return slice.call(array, n == null || guard ? 1 : n);
-  };
-
-  // Trim out all falsy values from an array.
-  _.compact = function(array) {
-    return _.filter(array, Boolean);
-  };
-
-  // Internal implementation of a recursive `flatten` function.
-  var flatten = function(input, shallow, strict, output) {
-    output = output || [];
-    var idx = output.length;
-    for (var i = 0, length = getLength(input); i < length; i++) {
-      var value = input[i];
-      if (isArrayLike(value) && (_.isArray(value) || _.isArguments(value))) {
-        // Flatten current level of array or arguments object.
-        if (shallow) {
-          var j = 0, len = value.length;
-          while (j < len) output[idx++] = value[j++];
-        } else {
-          flatten(value, shallow, strict, output);
-          idx = output.length;
-        }
-      } else if (!strict) {
-        output[idx++] = value;
-      }
-    }
-    return output;
-  };
-
-  // Flatten out an array, either recursively (by default), or just one level.
-  _.flatten = function(array, shallow) {
-    return flatten(array, shallow, false);
-  };
-
-  // Return a version of the array that does not contain the specified value(s).
-  _.without = restArguments(function(array, otherArrays) {
-    return _.difference(array, otherArrays);
-  });
-
-  // Produce a duplicate-free version of the array. If the array has already
-  // been sorted, you have the option of using a faster algorithm.
-  // The faster algorithm will not work with an iteratee if the iteratee
-  // is not a one-to-one function, so providing an iteratee will disable
-  // the faster algorithm.
-  // Aliased as `unique`.
-  _.uniq = _.unique = function(array, isSorted, iteratee, context) {
-    if (!_.isBoolean(isSorted)) {
-      context = iteratee;
-      iteratee = isSorted;
-      isSorted = false;
-    }
-    if (iteratee != null) iteratee = cb(iteratee, context);
-    var result = [];
-    var seen = [];
-    for (var i = 0, length = getLength(array); i < length; i++) {
-      var value = array[i],
-          computed = iteratee ? iteratee(value, i, array) : value;
-      if (isSorted && !iteratee) {
-        if (!i || seen !== computed) result.push(value);
-        seen = computed;
-      } else if (iteratee) {
-        if (!_.contains(seen, computed)) {
-          seen.push(computed);
-          result.push(value);
-        }
-      } else if (!_.contains(result, value)) {
-        result.push(value);
-      }
-    }
-    return result;
-  };
-
-  // Produce an array that contains the union: each distinct element from all of
-  // the passed-in arrays.
-  _.union = restArguments(function(arrays) {
-    return _.uniq(flatten(arrays, true, true));
-  });
-
-  // Produce an array that contains every item shared between all the
-  // passed-in arrays.
-  _.intersection = function(array) {
-    var result = [];
-    var argsLength = arguments.length;
-    for (var i = 0, length = getLength(array); i < length; i++) {
-      var item = array[i];
-      if (_.contains(result, item)) continue;
-      var j;
-      for (j = 1; j < argsLength; j++) {
-        if (!_.contains(arguments[j], item)) break;
-      }
-      if (j === argsLength) result.push(item);
-    }
-    return result;
-  };
-
-  // Take the difference between one array and a number of other arrays.
-  // Only the elements present in just the first array will remain.
-  _.difference = restArguments(function(array, rest) {
-    rest = flatten(rest, true, true);
-    return _.filter(array, function(value){
-      return !_.contains(rest, value);
-    });
-  });
-
-  // Complement of _.zip. Unzip accepts an array of arrays and groups
-  // each array's elements on shared indices.
-  _.unzip = function(array) {
-    var length = array && _.max(array, getLength).length || 0;
-    var result = Array(length);
-
-    for (var index = 0; index < length; index++) {
-      result[index] = _.pluck(array, index);
-    }
-    return result;
-  };
-
-  // Zip together multiple lists into a single array -- elements that share
-  // an index go together.
-  _.zip = restArguments(_.unzip);
-
-  // Converts lists into objects. Pass either a single array of `[key, value]`
-  // pairs, or two parallel arrays of the same length -- one of keys, and one of
-  // the corresponding values. Passing by pairs is the reverse of _.pairs.
-  _.object = function(list, values) {
-    var result = {};
-    for (var i = 0, length = getLength(list); i < length; i++) {
-      if (values) {
-        result[list[i]] = values[i];
-      } else {
-        result[list[i][0]] = list[i][1];
-      }
-    }
-    return result;
-  };
-
-  // Generator function to create the findIndex and findLastIndex functions.
-  var createPredicateIndexFinder = function(dir) {
-    return function(array, predicate, context) {
-      predicate = cb(predicate, context);
-      var length = getLength(array);
-      var index = dir > 0 ? 0 : length - 1;
-      for (; index >= 0 && index < length; index += dir) {
-        if (predicate(array[index], index, array)) return index;
-      }
-      return -1;
-    };
-  };
-
-  // Returns the first index on an array-like that passes a predicate test.
-  _.findIndex = createPredicateIndexFinder(1);
-  _.findLastIndex = createPredicateIndexFinder(-1);
-
-  // Use a comparator function to figure out the smallest index at which
-  // an object should be inserted so as to maintain order. Uses binary search.
-  _.sortedIndex = function(array, obj, iteratee, context) {
-    iteratee = cb(iteratee, context, 1);
-    var value = iteratee(obj);
-    var low = 0, high = getLength(array);
-    while (low < high) {
-      var mid = Math.floor((low + high) / 2);
-      if (iteratee(array[mid]) < value) low = mid + 1; else high = mid;
-    }
-    return low;
-  };
-
-  // Generator function to create the indexOf and lastIndexOf functions.
-  var createIndexFinder = function(dir, predicateFind, sortedIndex) {
-    return function(array, item, idx) {
-      var i = 0, length = getLength(array);
-      if (typeof idx == 'number') {
-        if (dir > 0) {
-          i = idx >= 0 ? idx : Math.max(idx + length, i);
-        } else {
-          length = idx >= 0 ? Math.min(idx + 1, length) : idx + length + 1;
-        }
-      } else if (sortedIndex && idx && length) {
-        idx = sortedIndex(array, item);
-        return array[idx] === item ? idx : -1;
-      }
-      if (item !== item) {
-        idx = predicateFind(slice.call(array, i, length), _.isNaN);
-        return idx >= 0 ? idx + i : -1;
-      }
-      for (idx = dir > 0 ? i : length - 1; idx >= 0 && idx < length; idx += dir) {
-        if (array[idx] === item) return idx;
-      }
-      return -1;
-    };
-  };
-
-  // Return the position of the first occurrence of an item in an array,
-  // or -1 if the item is not included in the array.
-  // If the array is large and already in sort order, pass `true`
-  // for **isSorted** to use binary search.
-  _.indexOf = createIndexFinder(1, _.findIndex, _.sortedIndex);
-  _.lastIndexOf = createIndexFinder(-1, _.findLastIndex);
-
-  // Generate an integer Array containing an arithmetic progression. A port of
-  // the native Python `range()` function. See
-  // [the Python documentation](http://docs.python.org/library/functions.html#range).
-  _.range = function(start, stop, step) {
-    if (stop == null) {
-      stop = start || 0;
-      start = 0;
-    }
-    if (!step) {
-      step = stop < start ? -1 : 1;
-    }
-
-    var length = Math.max(Math.ceil((stop - start) / step), 0);
-    var range = Array(length);
-
-    for (var idx = 0; idx < length; idx++, start += step) {
-      range[idx] = start;
-    }
-
-    return range;
-  };
-
-  // Chunk a single array into multiple arrays, each containing `count` or fewer
-  // items.
-  _.chunk = function(array, count) {
-    if (count == null || count < 1) return [];
-    var result = [];
-    var i = 0, length = array.length;
-    while (i < length) {
-      result.push(slice.call(array, i, i += count));
-    }
-    return result;
-  };
-
-  // Function (ahem) Functions
-  // ------------------
-
-  // Determines whether to execute a function as a constructor
-  // or a normal function with the provided arguments.
-  var executeBound = function(sourceFunc, boundFunc, context, callingContext, args) {
-    if (!(callingContext instanceof boundFunc)) return sourceFunc.apply(context, args);
-    var self = baseCreate(sourceFunc.prototype);
-    var result = sourceFunc.apply(self, args);
-    if (_.isObject(result)) return result;
-    return self;
-  };
-
-  // Create a function bound to a given object (assigning `this`, and arguments,
-  // optionally). Delegates to **ECMAScript 5**'s native `Function.bind` if
-  // available.
-  _.bind = restArguments(function(func, context, args) {
-    if (!_.isFunction(func)) throw new TypeError('Bind must be called on a function');
-    var bound = restArguments(function(callArgs) {
-      return executeBound(func, bound, context, this, args.concat(callArgs));
-    });
-    return bound;
-  });
-
-  // Partially apply a function by creating a version that has had some of its
-  // arguments pre-filled, without changing its dynamic `this` context. _ acts
-  // as a placeholder by default, allowing any combination of arguments to be
-  // pre-filled. Set `_.partial.placeholder` for a custom placeholder argument.
-  _.partial = restArguments(function(func, boundArgs) {
-    var placeholder = _.partial.placeholder;
-    var bound = function() {
-      var position = 0, length = boundArgs.length;
-      var args = Array(length);
-      for (var i = 0; i < length; i++) {
-        args[i] = boundArgs[i] === placeholder ? arguments[position++] : boundArgs[i];
-      }
-      while (position < arguments.length) args.push(arguments[position++]);
-      return executeBound(func, bound, this, this, args);
-    };
-    return bound;
-  });
-
-  _.partial.placeholder = _;
-
-  // Bind a number of an object's methods to that object. Remaining arguments
-  // are the method names to be bound. Useful for ensuring that all callbacks
-  // defined on an object belong to it.
-  _.bindAll = restArguments(function(obj, keys) {
-    keys = flatten(keys, false, false);
-    var index = keys.length;
-    if (index < 1) throw new Error('bindAll must be passed function names');
-    while (index--) {
-      var key = keys[index];
-      obj[key] = _.bind(obj[key], obj);
-    }
-  });
-
-  // Memoize an expensive function by storing its results.
-  _.memoize = function(func, hasher) {
-    var memoize = function(key) {
-      var cache = memoize.cache;
-      var address = '' + (hasher ? hasher.apply(this, arguments) : key);
-      if (!has(cache, address)) cache[address] = func.apply(this, arguments);
-      return cache[address];
-    };
-    memoize.cache = {};
-    return memoize;
-  };
-
-  // Delays a function for the given number of milliseconds, and then calls
-  // it with the arguments supplied.
-  _.delay = restArguments(function(func, wait, args) {
-    return setTimeout(function() {
-      return func.apply(null, args);
-    }, wait);
-  });
-
-  // Defers a function, scheduling it to run after the current call stack has
-  // cleared.
-  _.defer = _.partial(_.delay, _, 1);
-
-  // Returns a function, that, when invoked, will only be triggered at most once
-  // during a given window of time. Normally, the throttled function will run
-  // as much as it can, without ever going more than once per `wait` duration;
-  // but if you'd like to disable the execution on the leading edge, pass
-  // `{leading: false}`. To disable execution on the trailing edge, ditto.
-  _.throttle = function(func, wait, options) {
-    var timeout, context, args, result;
-    var previous = 0;
-    if (!options) options = {};
-
-    var later = function() {
-      previous = options.leading === false ? 0 : _.now();
-      timeout = null;
-      result = func.apply(context, args);
-      if (!timeout) context = args = null;
-    };
-
-    var throttled = function() {
-      var now = _.now();
-      if (!previous && options.leading === false) previous = now;
-      var remaining = wait - (now - previous);
-      context = this;
-      args = arguments;
-      if (remaining <= 0 || remaining > wait) {
-        if (timeout) {
-          clearTimeout(timeout);
-          timeout = null;
-        }
-        previous = now;
-        result = func.apply(context, args);
-        if (!timeout) context = args = null;
-      } else if (!timeout && options.trailing !== false) {
-        timeout = setTimeout(later, remaining);
-      }
-      return result;
-    };
-
-    throttled.cancel = function() {
-      clearTimeout(timeout);
-      previous = 0;
-      timeout = context = args = null;
-    };
-
-    return throttled;
-  };
-
-  // Returns a function, that, as long as it continues to be invoked, will not
-  // be triggered. The function will be called after it stops being called for
-  // N milliseconds. If `immediate` is passed, trigger the function on the
-  // leading edge, instead of the trailing.
-  _.debounce = function(func, wait, immediate) {
-    var timeout, result;
-
-    var later = function(context, args) {
-      timeout = null;
-      if (args) result = func.apply(context, args);
-    };
-
-    var debounced = restArguments(function(args) {
-      if (timeout) clearTimeout(timeout);
-      if (immediate) {
-        var callNow = !timeout;
-        timeout = setTimeout(later, wait);
-        if (callNow) result = func.apply(this, args);
-      } else {
-        timeout = _.delay(later, wait, this, args);
-      }
-
-      return result;
-    });
-
-    debounced.cancel = function() {
-      clearTimeout(timeout);
-      timeout = null;
-    };
-
-    return debounced;
-  };
-
-  // Returns the first function passed as an argument to the second,
-  // allowing you to adjust arguments, run code before and after, and
-  // conditionally execute the original function.
-  _.wrap = function(func, wrapper) {
-    return _.partial(wrapper, func);
-  };
-
-  // Returns a negated version of the passed-in predicate.
-  _.negate = function(predicate) {
-    return function() {
-      return !predicate.apply(this, arguments);
-    };
-  };
-
-  // Returns a function that is the composition of a list of functions, each
-  // consuming the return value of the function that follows.
-  _.compose = function() {
-    var args = arguments;
-    var start = args.length - 1;
-    return function() {
-      var i = start;
-      var result = args[start].apply(this, arguments);
-      while (i--) result = args[i].call(this, result);
-      return result;
-    };
-  };
-
-  // Returns a function that will only be executed on and after the Nth call.
-  _.after = function(times, func) {
-    return function() {
-      if (--times < 1) {
-        return func.apply(this, arguments);
-      }
-    };
-  };
-
-  // Returns a function that will only be executed up to (but not including) the Nth call.
-  _.before = function(times, func) {
-    var memo;
-    return function() {
-      if (--times > 0) {
-        memo = func.apply(this, arguments);
-      }
-      if (times <= 1) func = null;
-      return memo;
-    };
-  };
-
-  // Returns a function that will be executed at most one time, no matter how
-  // often you call it. Useful for lazy initialization.
-  _.once = _.partial(_.before, 2);
-
-  _.restArguments = restArguments;
-
-  // Object Functions
-  // ----------------
-
-  // Keys in IE < 9 that won't be iterated by `for key in ...` and thus missed.
-  var hasEnumBug = !{toString: null}.propertyIsEnumerable('toString');
-  var nonEnumerableProps = ['valueOf', 'isPrototypeOf', 'toString',
-    'propertyIsEnumerable', 'hasOwnProperty', 'toLocaleString'];
-
-  var collectNonEnumProps = function(obj, keys) {
-    var nonEnumIdx = nonEnumerableProps.length;
-    var constructor = obj.constructor;
-    var proto = _.isFunction(constructor) && constructor.prototype || ObjProto;
-
-    // Constructor is a special case.
-    var prop = 'constructor';
-    if (has(obj, prop) && !_.contains(keys, prop)) keys.push(prop);
-
-    while (nonEnumIdx--) {
-      prop = nonEnumerableProps[nonEnumIdx];
-      if (prop in obj && obj[prop] !== proto[prop] && !_.contains(keys, prop)) {
-        keys.push(prop);
-      }
-    }
-  };
-
-  // Retrieve the names of an object's own properties.
-  // Delegates to **ECMAScript 5**'s native `Object.keys`.
-  _.keys = function(obj) {
-    if (!_.isObject(obj)) return [];
-    if (nativeKeys) return nativeKeys(obj);
-    var keys = [];
-    for (var key in obj) if (has(obj, key)) keys.push(key);
-    // Ahem, IE < 9.
-    if (hasEnumBug) collectNonEnumProps(obj, keys);
-    return keys;
-  };
-
-  // Retrieve all the property names of an object.
-  _.allKeys = function(obj) {
-    if (!_.isObject(obj)) return [];
-    var keys = [];
-    for (var key in obj) keys.push(key);
-    // Ahem, IE < 9.
-    if (hasEnumBug) collectNonEnumProps(obj, keys);
-    return keys;
-  };
-
-  // Retrieve the values of an object's properties.
-  _.values = function(obj) {
-    var keys = _.keys(obj);
-    var length = keys.length;
-    var values = Array(length);
-    for (var i = 0; i < length; i++) {
-      values[i] = obj[keys[i]];
-    }
-    return values;
-  };
-
-  // Returns the results of applying the iteratee to each element of the object.
-  // In contrast to _.map it returns an object.
-  _.mapObject = function(obj, iteratee, context) {
-    iteratee = cb(iteratee, context);
-    var keys = _.keys(obj),
-        length = keys.length,
-        results = {};
-    for (var index = 0; index < length; index++) {
-      var currentKey = keys[index];
-      results[currentKey] = iteratee(obj[currentKey], currentKey, obj);
-    }
-    return results;
-  };
-
-  // Convert an object into a list of `[key, value]` pairs.
-  // The opposite of _.object.
-  _.pairs = function(obj) {
-    var keys = _.keys(obj);
-    var length = keys.length;
-    var pairs = Array(length);
-    for (var i = 0; i < length; i++) {
-      pairs[i] = [keys[i], obj[keys[i]]];
-    }
-    return pairs;
-  };
-
-  // Invert the keys and values of an object. The values must be serializable.
-  _.invert = function(obj) {
-    var result = {};
-    var keys = _.keys(obj);
-    for (var i = 0, length = keys.length; i < length; i++) {
-      result[obj[keys[i]]] = keys[i];
-    }
-    return result;
-  };
-
-  // Return a sorted list of the function names available on the object.
-  // Aliased as `methods`.
-  _.functions = _.methods = function(obj) {
-    var names = [];
-    for (var key in obj) {
-      if (_.isFunction(obj[key])) names.push(key);
-    }
-    return names.sort();
-  };
-
-  // An internal function for creating assigner functions.
-  var createAssigner = function(keysFunc, defaults) {
-    return function(obj) {
-      var length = arguments.length;
-      if (defaults) obj = Object(obj);
-      if (length < 2 || obj == null) return obj;
-      for (var index = 1; index < length; index++) {
-        var source = arguments[index],
-            keys = keysFunc(source),
-            l = keys.length;
-        for (var i = 0; i < l; i++) {
-          var key = keys[i];
-          if (!defaults || obj[key] === void 0) obj[key] = source[key];
-        }
-      }
-      return obj;
-    };
-  };
-
-  // Extend a given object with all the properties in passed-in object(s).
-  _.extend = createAssigner(_.allKeys);
-
-  // Assigns a given object with all the own properties in the passed-in object(s).
-  // (https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object/assign)
-  _.extendOwn = _.assign = createAssigner(_.keys);
-
-  // Returns the first key on an object that passes a predicate test.
-  _.findKey = function(obj, predicate, context) {
-    predicate = cb(predicate, context);
-    var keys = _.keys(obj), key;
-    for (var i = 0, length = keys.length; i < length; i++) {
-      key = keys[i];
-      if (predicate(obj[key], key, obj)) return key;
-    }
-  };
-
-  // Internal pick helper function to determine if `obj` has key `key`.
-  var keyInObj = function(value, key, obj) {
-    return key in obj;
-  };
-
-  // Return a copy of the object only containing the whitelisted properties.
-  _.pick = restArguments(function(obj, keys) {
-    var result = {}, iteratee = keys[0];
-    if (obj == null) return result;
-    if (_.isFunction(iteratee)) {
-      if (keys.length > 1) iteratee = optimizeCb(iteratee, keys[1]);
-      keys = _.allKeys(obj);
-    } else {
-      iteratee = keyInObj;
-      keys = flatten(keys, false, false);
-      obj = Object(obj);
-    }
-    for (var i = 0, length = keys.length; i < length; i++) {
-      var key = keys[i];
-      var value = obj[key];
-      if (iteratee(value, key, obj)) result[key] = value;
-    }
-    return result;
-  });
-
-  // Return a copy of the object without the blacklisted properties.
-  _.omit = restArguments(function(obj, keys) {
-    var iteratee = keys[0], context;
-    if (_.isFunction(iteratee)) {
-      iteratee = _.negate(iteratee);
-      if (keys.length > 1) context = keys[1];
-    } else {
-      keys = _.map(flatten(keys, false, false), String);
-      iteratee = function(value, key) {
-        return !_.contains(keys, key);
-      };
-    }
-    return _.pick(obj, iteratee, context);
-  });
-
-  // Fill in a given object with default properties.
-  _.defaults = createAssigner(_.allKeys, true);
-
-  // Creates an object that inherits from the given prototype object.
-  // If additional properties are provided then they will be added to the
-  // created object.
-  _.create = function(prototype, props) {
-    var result = baseCreate(prototype);
-    if (props) _.extendOwn(result, props);
-    return result;
-  };
-
-  // Create a (shallow-cloned) duplicate of an object.
-  _.clone = function(obj) {
-    if (!_.isObject(obj)) return obj;
-    return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
-  };
-
-  // Invokes interceptor with the obj, and then returns obj.
-  // The primary purpose of this method is to "tap into" a method chain, in
-  // order to perform operations on intermediate results within the chain.
-  _.tap = function(obj, interceptor) {
-    interceptor(obj);
-    return obj;
-  };
-
-  // Returns whether an object has a given set of `key:value` pairs.
-  _.isMatch = function(object, attrs) {
-    var keys = _.keys(attrs), length = keys.length;
-    if (object == null) return !length;
-    var obj = Object(object);
-    for (var i = 0; i < length; i++) {
-      var key = keys[i];
-      if (attrs[key] !== obj[key] || !(key in obj)) return false;
-    }
-    return true;
-  };
-
-
-  // Internal recursive comparison function for `isEqual`.
-  var eq, deepEq;
-  eq = function(a, b, aStack, bStack) {
-    // Identical objects are equal. `0 === -0`, but they aren't identical.
-    // See the [Harmony `egal` proposal](http://wiki.ecmascript.org/doku.php?id=harmony:egal).
-    if (a === b) return a !== 0 || 1 / a === 1 / b;
-    // `null` or `undefined` only equal to itself (strict comparison).
-    if (a == null || b == null) return false;
-    // `NaN`s are equivalent, but non-reflexive.
-    if (a !== a) return b !== b;
-    // Exhaust primitive checks
-    var type = typeof a;
-    if (type !== 'function' && type !== 'object' && typeof b != 'object') return false;
-    return deepEq(a, b, aStack, bStack);
-  };
-
-  // Internal recursive comparison function for `isEqual`.
-  deepEq = function(a, b, aStack, bStack) {
-    // Unwrap any wrapped objects.
-    if (a instanceof _) a = a._wrapped;
-    if (b instanceof _) b = b._wrapped;
-    // Compare `[[Class]]` names.
-    var className = toString.call(a);
-    if (className !== toString.call(b)) return false;
-    switch (className) {
-      // Strings, numbers, regular expressions, dates, and booleans are compared by value.
-      case '[object RegExp]':
-      // RegExps are coerced to strings for comparison (Note: '' + /a/i === '/a/i')
-      case '[object String]':
-        // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
-        // equivalent to `new String("5")`.
-        return '' + a === '' + b;
-      case '[object Number]':
-        // `NaN`s are equivalent, but non-reflexive.
-        // Object(NaN) is equivalent to NaN.
-        if (+a !== +a) return +b !== +b;
-        // An `egal` comparison is performed for other numeric values.
-        return +a === 0 ? 1 / +a === 1 / b : +a === +b;
-      case '[object Date]':
-      case '[object Boolean]':
-        // Coerce dates and booleans to numeric primitive values. Dates are compared by their
-        // millisecond representations. Note that invalid dates with millisecond representations
-        // of `NaN` are not equivalent.
-        return +a === +b;
-      case '[object Symbol]':
-        return SymbolProto.valueOf.call(a) === SymbolProto.valueOf.call(b);
-    }
-
-    var areArrays = className === '[object Array]';
-    if (!areArrays) {
-      if (typeof a != 'object' || typeof b != 'object') return false;
-
-      // Objects with different constructors are not equivalent, but `Object`s or `Array`s
-      // from different frames are.
-      var aCtor = a.constructor, bCtor = b.constructor;
-      if (aCtor !== bCtor && !(_.isFunction(aCtor) && aCtor instanceof aCtor &&
-                               _.isFunction(bCtor) && bCtor instanceof bCtor)
-                          && ('constructor' in a && 'constructor' in b)) {
-        return false;
-      }
-    }
-    // Assume equality for cyclic structures. The algorithm for detecting cyclic
-    // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
-
-    // Initializing stack of traversed objects.
-    // It's done here since we only need them for objects and arrays comparison.
-    aStack = aStack || [];
-    bStack = bStack || [];
-    var length = aStack.length;
-    while (length--) {
-      // Linear search. Performance is inversely proportional to the number of
-      // unique nested structures.
-      if (aStack[length] === a) return bStack[length] === b;
-    }
-
-    // Add the first object to the stack of traversed objects.
-    aStack.push(a);
-    bStack.push(b);
-
-    // Recursively compare objects and arrays.
-    if (areArrays) {
-      // Compare array lengths to determine if a deep comparison is necessary.
-      length = a.length;
-      if (length !== b.length) return false;
-      // Deep compare the contents, ignoring non-numeric properties.
-      while (length--) {
-        if (!eq(a[length], b[length], aStack, bStack)) return false;
-      }
-    } else {
-      // Deep compare objects.
-      var keys = _.keys(a), key;
-      length = keys.length;
-      // Ensure that both objects contain the same number of properties before comparing deep equality.
-      if (_.keys(b).length !== length) return false;
-      while (length--) {
-        // Deep compare each member
-        key = keys[length];
-        if (!(has(b, key) && eq(a[key], b[key], aStack, bStack))) return false;
-      }
-    }
-    // Remove the first object from the stack of traversed objects.
-    aStack.pop();
-    bStack.pop();
-    return true;
-  };
-
-  // Perform a deep comparison to check if two objects are equal.
-  _.isEqual = function(a, b) {
-    return eq(a, b);
-  };
-
-  // Is a given array, string, or object empty?
-  // An "empty" object has no enumerable own-properties.
-  _.isEmpty = function(obj) {
-    if (obj == null) return true;
-    if (isArrayLike(obj) && (_.isArray(obj) || _.isString(obj) || _.isArguments(obj))) return obj.length === 0;
-    return _.keys(obj).length === 0;
-  };
-
-  // Is a given value a DOM element?
-  _.isElement = function(obj) {
-    return !!(obj && obj.nodeType === 1);
-  };
-
-  // Is a given value an array?
-  // Delegates to ECMA5's native Array.isArray
-  _.isArray = nativeIsArray || function(obj) {
-    return toString.call(obj) === '[object Array]';
-  };
-
-  // Is a given variable an object?
-  _.isObject = function(obj) {
-    var type = typeof obj;
-    return type === 'function' || type === 'object' && !!obj;
-  };
-
-  // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp, isError, isMap, isWeakMap, isSet, isWeakSet.
-  _.each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp', 'Error', 'Symbol', 'Map', 'WeakMap', 'Set', 'WeakSet'], function(name) {
-    _['is' + name] = function(obj) {
-      return toString.call(obj) === '[object ' + name + ']';
-    };
-  });
-
-  // Define a fallback version of the method in browsers (ahem, IE < 9), where
-  // there isn't any inspectable "Arguments" type.
-  if (!_.isArguments(arguments)) {
-    _.isArguments = function(obj) {
-      return has(obj, 'callee');
-    };
-  }
-
-  // Optimize `isFunction` if appropriate. Work around some typeof bugs in old v8,
-  // IE 11 (#1621), Safari 8 (#1929), and PhantomJS (#2236).
-  var nodelist = root.document && root.document.childNodes;
-  if (typeof /./ != 'function' && typeof Int8Array != 'object' && typeof nodelist != 'function') {
-    _.isFunction = function(obj) {
-      return typeof obj == 'function' || false;
-    };
-  }
-
-  // Is a given object a finite number?
-  _.isFinite = function(obj) {
-    return !_.isSymbol(obj) && isFinite(obj) && !isNaN(parseFloat(obj));
-  };
-
-  // Is the given value `NaN`?
-  _.isNaN = function(obj) {
-    return _.isNumber(obj) && isNaN(obj);
-  };
-
-  // Is a given value a boolean?
-  _.isBoolean = function(obj) {
-    return obj === true || obj === false || toString.call(obj) === '[object Boolean]';
-  };
-
-  // Is a given value equal to null?
-  _.isNull = function(obj) {
-    return obj === null;
-  };
-
-  // Is a given variable undefined?
-  _.isUndefined = function(obj) {
-    return obj === void 0;
-  };
-
-  // Shortcut function for checking if an object has a given property directly
-  // on itself (in other words, not on a prototype).
-  _.has = function(obj, path) {
-    if (!_.isArray(path)) {
-      return has(obj, path);
-    }
-    var length = path.length;
-    for (var i = 0; i < length; i++) {
-      var key = path[i];
-      if (obj == null || !hasOwnProperty.call(obj, key)) {
-        return false;
-      }
-      obj = obj[key];
-    }
-    return !!length;
-  };
-
-  // Utility Functions
-  // -----------------
-
-  // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
-  // previous owner. Returns a reference to the Underscore object.
-  _.noConflict = function() {
-    root._ = previousUnderscore;
-    return this;
-  };
-
-  // Keep the identity function around for default iteratees.
-  _.identity = function(value) {
-    return value;
-  };
-
-  // Predicate-generating functions. Often useful outside of Underscore.
-  _.constant = function(value) {
-    return function() {
-      return value;
-    };
-  };
-
-  _.noop = function(){};
-
-  // Creates a function that, when passed an object, will traverse that object’s
-  // properties down the given `path`, specified as an array of keys or indexes.
-  _.property = function(path) {
-    if (!_.isArray(path)) {
-      return shallowProperty(path);
-    }
-    return function(obj) {
-      return deepGet(obj, path);
-    };
-  };
-
-  // Generates a function for a given object that returns a given property.
-  _.propertyOf = function(obj) {
-    if (obj == null) {
-      return function(){};
-    }
-    return function(path) {
-      return !_.isArray(path) ? obj[path] : deepGet(obj, path);
-    };
-  };
-
-  // Returns a predicate for checking whether an object has a given set of
-  // `key:value` pairs.
-  _.matcher = _.matches = function(attrs) {
-    attrs = _.extendOwn({}, attrs);
-    return function(obj) {
-      return _.isMatch(obj, attrs);
-    };
-  };
-
-  // Run a function **n** times.
-  _.times = function(n, iteratee, context) {
-    var accum = Array(Math.max(0, n));
-    iteratee = optimizeCb(iteratee, context, 1);
-    for (var i = 0; i < n; i++) accum[i] = iteratee(i);
-    return accum;
-  };
-
-  // Return a random integer between min and max (inclusive).
-  _.random = function(min, max) {
-    if (max == null) {
-      max = min;
-      min = 0;
-    }
-    return min + Math.floor(Math.random() * (max - min + 1));
-  };
-
-  // A (possibly faster) way to get the current timestamp as an integer.
-  _.now = Date.now || function() {
-    return new Date().getTime();
-  };
-
-  // List of HTML entities for escaping.
-  var escapeMap = {
-    '&': '&amp;',
-    '<': '&lt;',
-    '>': '&gt;',
-    '"': '&quot;',
-    "'": '&#x27;',
-    '`': '&#x60;'
-  };
-  var unescapeMap = _.invert(escapeMap);
-
-  // Functions for escaping and unescaping strings to/from HTML interpolation.
-  var createEscaper = function(map) {
-    var escaper = function(match) {
-      return map[match];
-    };
-    // Regexes for identifying a key that needs to be escaped.
-    var source = '(?:' + _.keys(map).join('|') + ')';
-    var testRegexp = RegExp(source);
-    var replaceRegexp = RegExp(source, 'g');
-    return function(string) {
-      string = string == null ? '' : '' + string;
-      return testRegexp.test(string) ? string.replace(replaceRegexp, escaper) : string;
-    };
-  };
-  _.escape = createEscaper(escapeMap);
-  _.unescape = createEscaper(unescapeMap);
-
-  // Traverses the children of `obj` along `path`. If a child is a function, it
-  // is invoked with its parent as context. Returns the value of the final
-  // child, or `fallback` if any child is undefined.
-  _.result = function(obj, path, fallback) {
-    if (!_.isArray(path)) path = [path];
-    var length = path.length;
-    if (!length) {
-      return _.isFunction(fallback) ? fallback.call(obj) : fallback;
-    }
-    for (var i = 0; i < length; i++) {
-      var prop = obj == null ? void 0 : obj[path[i]];
-      if (prop === void 0) {
-        prop = fallback;
-        i = length; // Ensure we don't continue iterating.
-      }
-      obj = _.isFunction(prop) ? prop.call(obj) : prop;
-    }
-    return obj;
-  };
-
-  // Generate a unique integer id (unique within the entire client session).
-  // Useful for temporary DOM ids.
-  var idCounter = 0;
-  _.uniqueId = function(prefix) {
-    var id = ++idCounter + '';
-    return prefix ? prefix + id : id;
-  };
-
-  // By default, Underscore uses ERB-style template delimiters, change the
-  // following template settings to use alternative delimiters.
-  _.templateSettings = {
-    evaluate: /<%([\s\S]+?)%>/g,
-    interpolate: /<%=([\s\S]+?)%>/g,
-    escape: /<%-([\s\S]+?)%>/g
-  };
-
-  // When customizing `templateSettings`, if you don't want to define an
-  // interpolation, evaluation or escaping regex, we need one that is
-  // guaranteed not to match.
-  var noMatch = /(.)^/;
-
-  // Certain characters need to be escaped so that they can be put into a
-  // string literal.
-  var escapes = {
-    "'": "'",
-    '\\': '\\',
-    '\r': 'r',
-    '\n': 'n',
-    '\u2028': 'u2028',
-    '\u2029': 'u2029'
-  };
-
-  var escapeRegExp = /\\|'|\r|\n|\u2028|\u2029/g;
-
-  var escapeChar = function(match) {
-    return '\\' + escapes[match];
-  };
-
-  // JavaScript micro-templating, similar to John Resig's implementation.
-  // Underscore templating handles arbitrary delimiters, preserves whitespace,
-  // and correctly escapes quotes within interpolated code.
-  // NB: `oldSettings` only exists for backwards compatibility.
-  _.template = function(text, settings, oldSettings) {
-    if (!settings && oldSettings) settings = oldSettings;
-    settings = _.defaults({}, settings, _.templateSettings);
-
-    // Combine delimiters into one regular expression via alternation.
-    var matcher = RegExp([
-      (settings.escape || noMatch).source,
-      (settings.interpolate || noMatch).source,
-      (settings.evaluate || noMatch).source
-    ].join('|') + '|$', 'g');
-
-    // Compile the template source, escaping string literals appropriately.
-    var index = 0;
-    var source = "__p+='";
-    text.replace(matcher, function(match, escape, interpolate, evaluate, offset) {
-      source += text.slice(index, offset).replace(escapeRegExp, escapeChar);
-      index = offset + match.length;
-
-      if (escape) {
-        source += "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'";
-      } else if (interpolate) {
-        source += "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'";
-      } else if (evaluate) {
-        source += "';\n" + evaluate + "\n__p+='";
-      }
-
-      // Adobe VMs need the match returned to produce the correct offset.
-      return match;
-    });
-    source += "';\n";
-
-    // If a variable is not specified, place data values in local scope.
-    if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';
-
-    source = "var __t,__p='',__j=Array.prototype.join," +
-      "print=function(){__p+=__j.call(arguments,'');};\n" +
-      source + 'return __p;\n';
-
-    var render;
-    try {
-      render = new Function(settings.variable || 'obj', '_', source);
-    } catch (e) {
-      e.source = source;
-      throw e;
-    }
-
-    var template = function(data) {
-      return render.call(this, data, _);
-    };
-
-    // Provide the compiled source as a convenience for precompilation.
-    var argument = settings.variable || 'obj';
-    template.source = 'function(' + argument + '){\n' + source + '}';
-
-    return template;
-  };
-
-  // Add a "chain" function. Start chaining a wrapped Underscore object.
-  _.chain = function(obj) {
-    var instance = _(obj);
-    instance._chain = true;
-    return instance;
-  };
-
-  // OOP
-  // ---------------
-  // If Underscore is called as a function, it returns a wrapped object that
-  // can be used OO-style. This wrapper holds altered versions of all the
-  // underscore functions. Wrapped objects may be chained.
-
-  // Helper function to continue chaining intermediate results.
-  var chainResult = function(instance, obj) {
-    return instance._chain ? _(obj).chain() : obj;
-  };
-
-  // Add your own custom functions to the Underscore object.
-  _.mixin = function(obj) {
-    _.each(_.functions(obj), function(name) {
-      var func = _[name] = obj[name];
-      _.prototype[name] = function() {
-        var args = [this._wrapped];
-        push.apply(args, arguments);
-        return chainResult(this, func.apply(_, args));
-      };
-    });
-    return _;
-  };
-
-  // Add all of the Underscore functions to the wrapper object.
-  _.mixin(_);
-
-  // Add all mutator Array functions to the wrapper.
-  _.each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
-    var method = ArrayProto[name];
-    _.prototype[name] = function() {
-      var obj = this._wrapped;
-      method.apply(obj, arguments);
-      if ((name === 'shift' || name === 'splice') && obj.length === 0) delete obj[0];
-      return chainResult(this, obj);
-    };
-  });
-
-  // Add all accessor Array functions to the wrapper.
-  _.each(['concat', 'join', 'slice'], function(name) {
-    var method = ArrayProto[name];
-    _.prototype[name] = function() {
-      return chainResult(this, method.apply(this._wrapped, arguments));
-    };
-  });
-
-  // Extracts the result from a wrapped and chained object.
-  _.prototype.value = function() {
-    return this._wrapped;
-  };
-
-  // Provide unwrapping proxy for some methods used in engine operations
-  // such as arithmetic and JSON stringification.
-  _.prototype.valueOf = _.prototype.toJSON = _.prototype.value;
-
-  _.prototype.toString = function() {
-    return String(this._wrapped);
-  };
-
-  // AMD registration happens at the end for compatibility with AMD loaders
-  // that may not enforce next-turn semantics on modules. Even though general
-  // practice for AMD registration is to be anonymous, underscore registers
-  // as a named module because, like jQuery, it is a base library that is
-  // popular enough to be bundled in a third party lib, but not be part of
-  // an AMD load request. Those cases could generate an error when an
-  // anonymous define() is called outside of a loader request.
-  if (typeof define == 'function' && define.amd) {
-    define('underscore', [], function() {
-      return _;
-    });
-  }
-}());
diff --git a/services/web/webpack.config.js b/services/web/webpack.config.js
index 1e8de2690b..439153f051 100644
--- a/services/web/webpack.config.js
+++ b/services/web/webpack.config.js
@@ -167,11 +167,8 @@ module.exports = {
         ]
       },
       {
-        // Expose underscore global variable
-        test: path.join(
-          __dirname,
-          `frontend/js/vendor/libs/${PackageVersions.lib('underscore')}.js`
-        ),
+        // Expose lodash global variable
+        test: require.resolve('lodash'),
         use: [
           {
             loader: 'expose-loader',
@@ -257,11 +254,5 @@ module.exports = {
       // to provide support for non-Latin characters
       { from: 'node_modules/pdfjs-dist/cmaps', to: 'js/cmaps' }
     ])
-  ],
-
-  // If underscore is required by another dependency *don't* include in the
-  // bundle and use the relevant global variable instead
-  externals: {
-    underscore: '_'
-  }
+  ]
 }