// This is the code from the README. const OError = require('..') const demoDatabase = { findUser(id, callback) { process.nextTick(() => { // return result asynchronously if (id === 42) { callback(null, { name: 'Bob' }) } else { callback(new Error('not found')) } }) }, } function sayHi1(userId, callback) { demoDatabase.findUser(userId, (err, user) => { if (err) return callback(err) callback(null, 'Hi ' + user.name) }) } sayHi1(42, (err, result) => { if (err) { console.error(err) } else { console.log(result) } }) sayHi1(43, (err, result) => { if (err) { console.error(err) } else { console.log(result) } }) function sayHi2(userId, callback) { demoDatabase.findUser(userId, (err, user) => { if (err) return callback(OError.tag(err)) callback(null, 'Hi ' + user.name) }) } sayHi2(43, (err, result) => { if (err) { console.error(OError.getFullStack(OError.tag(err))) } else { console.log(result) } }) function sayHi3(userId, callback) { demoDatabase.findUser(userId, (err, user) => { if (err) return callback(OError.tag(err, 'failed to find user', { userId })) callback(null, 'Hi ' + user.name) }) } sayHi3(43, (err, result) => { if (err) { OError.tag(err, 'failed to say hi') console.error(OError.getFullStack(err)) console.error(OError.getFullInfo(err)) } else { console.log(result) } }) const promisify = require('node:util').promisify demoDatabase.findUserAsync = promisify(demoDatabase.findUser) async function sayHi4NoHandling(userId) { const user = await demoDatabase.findUserAsync(userId) return `Hi ${user.name}` } async function sayHi4(userId) { try { const user = await demoDatabase.findUserAsync(userId) return `Hi ${user.name}` } catch (error) { throw OError.tag(error, 'failed to find user', { userId }) } } async function main() { try { await sayHi4NoHandling(43) } catch (error) { console.error(OError.getFullStack(error)) console.error(OError.getFullInfo(error)) } try { await sayHi4(43) } catch (error) { OError.tag(error, 'failed to say hi') console.error(OError.getFullStack(error)) console.error(OError.getFullInfo(error)) } } main() class UserNotFoundError extends OError { constructor(userId) { super('user not found', { userId }) } } try { throw new UserNotFoundError(123) } catch (error) { console.error(OError.getFullStack(error)) console.error(OError.getFullInfo(error)) } async function sayHi5(userId) { try { const user = await demoDatabase.findUserAsync(userId) return `Hi ${user.name}` } catch (error) { if (error.message === 'not found') { throw new UserNotFoundError(userId).withCause(error) } } } async function main2() { try { await sayHi5(43) } catch (error) { OError.tag(error, 'failed to say hi') console.error(OError.getFullStack(error)) console.error(OError.getFullInfo(error)) } } main2()