Javascript has multiple ways you can store your data. Each of these different ways is called a data type, and they each carry different “methods” which are helpful commands. Today, I’ll show you the different data types and methods that I use and how they’re useful.
<!--more-->
This post is by far not a comprehenive list of all the Data types and their methods. If you want one of those, please check out [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects) and/or [WebPlatform](http://docs.webplatform.org/wiki/javascript/objects){.broken_link}. This is the second lecture of the web development class I’m teaching for the newer folks over at [Math I/O](http://math-io.com). Due to the nature of Math I/O (making math games and all), the next few posts will be Javascript centric. We’re getting ready to build a new game, so I want to prepare them as much as possible. \*Excited\* ^_^ Ilya Kantor does a good job of descibing Javascript data types and their many methods in [Mastering Data Types](http://javascript.info/tutorial/mastering-data-types) which I made the recommended reading for this lecture.
<pre><codeclass="language-javascript">var name = "Brandon";</code></pre>
You can access a character inside of a string by using [] notation. Inside the [] you put the index of the character you want. An index is the numeral location of the character starting from the left. It is important to note that Javascript starts counting from 0.
This can be used to find the index of any character(s) in a string. I primarily use it for when I need to check if something exists in a string. Do I have a ‘z’ in my name?
The replace method can replace any character(s) with other character(s). For more complex replacing, look into [Regular Expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions) and how you can use them in .replace(). Replace the first ‘n’ in my name with an ‘m’.
This method returns the string with all the lowercase characters converted to uppercase and can be useful for when you’re checking user input and you don’t want to worry about different cases.
##### <a href="#return-a-psuedo-random-number-[0,1)" name="return-a-psuedo-random-number-[0,1)"></a>Return a psuedo random number [0,1) {#return-a-psuedo-random-number-[0,1)}
##### <a href="#round-x-to-the-nearest-integer" name="round-x-to-the-nearest-integer"></a>Round x to the nearest integer {#round-x-to-the-nearest-integer}
Booleans are either <codeclass="language-javascript">true</code> or <codeclass="language-javascript">false and</code>are typically used in conditional statements. You can either create them explicitly
Combines two arrays, putting the items from the array in the parenthesis to the end of the main array. This method is a lot faster than grabbing each item by their index and adding them using the .push() method.
Converts the array into a string, with each item seperated by whatever is in the parenthesis. Useful for telling the user the items in their inventory, for example.
<pre><codeclass="language-javascript">
var inventory = ['books','apples','pencils'];
console.log("You have " + inventory.join(", ") + " in your inventory.");
</code></pre>
Logs <codeclass="language-javascript">"You have books, apples, pencils in your inventory."</code>
Objects are like arrays, however they’re easier for establishing the relationship between properties and their values. You can store any data type as a property of an object.
<pre><codeclass="language-javascript">
var player = {};
player.name = "Brandon";
player.health = Number.POSITIVE_INFINITY;
console.log(player.name + " has " + player.health + " health.");
</code></pre>
Logs <codeclass="language-javascript">"Brandon has Infinity health"</code> Yup that sounds about right.
All of the different data types in Javascript are tools for you to get the job done. When assigning a variable, think to yourself which tool you should use. I had fun doing this lecture. We finished earlier than expected, due to my extra preparations. (Still shuddering over my unpreparedness from last week). We had finished so early in fact, that I went ahead and started teaching next week’s material. Do not worry though, my lovely reader’s only get the most structured of lesson materials. So you’ll have to wait until next week to hear more. 🙂
