| const contrivedEx1 = str => { | |
| const trimmed = str.trim(); | |
| const number = parseInt(trimmed); | |
| const nextNumber = number + 1; | |
| return String.fromCharCode(nextNumber); | |
| } | |
| const contrivedEx1 = str => { | |
| [str.trim()] |
| const isUnique = (value, index, self) => self.indexOf(value) === index; | |
| const unique = items => items.filter(isUnique); | |
| const mapBy = (items, key) => items.map(item => item[key]); | |
| const uniqueKeys = (items, key) => unique(mapBy(items, key)); | |
| const someKeys = (item, keys) => keys.reduce((result, key) => { | |
| result[key] = item[key]; | |
| return result; | |
| }, {}); |
| function CreditCard(http) { | |
| this.process = function(cardType, cardNumber) { | |
| var cardProcessor = { | |
| "VISA": this.processVisa, | |
| "MASTERCARD": this.processMasterCard, | |
| "AMEX": this.processAmex | |
| }; | |
| cardProcessor[cardType](cardNumber); | |
| }; | |
| this.processVisa = function(cardNumber) { |
| let defaults = { file: null }; | |
| function foo(options) { | |
| // Merging defaults and options objects in ES6 | |
| options = [ defaults, options ].reduce(Object.assign, {}); | |
| } | |
| foo({ file: "happy.md" }); |
| class Maybe { | |
| constructor(val) { | |
| this.__val = val; | |
| this.__error = this.isError(); | |
| this.__defaultVal = null; | |
| } | |
| isError() { | |
| const val = this.__val; | |
| return (val === null) |
#Arrow Functions
Arrow functions (also known as fat arrow functions) are awesome. They do two main things for you. Create a shorter syntax, and lexically scope this.
##Shorter syntax
//ES5
[1, 2, 3].map(function(n){ return n + 1 } // [2, 3, 4]
//ES6
| The MIT License (MIT) | |
| Copyright (c) 2015 Justin Perry | |
| Permission is hereby granted, free of charge, to any person obtaining a copy of | |
| this software and associated documentation files (the "Software"), to deal in | |
| the Software without restriction, including without limitation the rights to | |
| use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of | |
| the Software, and to permit persons to whom the Software is furnished to do so, | |
| subject to the following conditions: |
This code is modified from the excellent O'Reilly book "Functional JavaScript". You should buy it, I highly recommend it! Don't kid yourself into thinking this gist even remotely covers the great content from a 200+ page technical book on the subject; it doesn't. Buy the book and get the in-depth knowledge for yourself. It's worth it.
| <!doctype html> | |
| <html ng-app='APP'> | |
| <head> | |
| <meta name="description" content="Angular Nested recursive directives" /> | |
| <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.1.5/angular.min.js"></script> | |
| </head> | |
| <body> | |
| <div ng-controller="IndexCtrl"> | |
| <button ng-click="groupByTour()">tours</button> | |
| <button ng-click="groupByOrders()">orders</button> |
| function groupByTour(orders) { | |
| return orders.reduce((result, order) => { | |
| const group = result.find(({ tour }) => tour.id === order.tour.id); | |
| group ? group.order.push(order) : result.push({ tour : order.tour, order : [order] }); | |
| return result; | |
| }, []) | |
| } |