Scenario You want to use just the methods you like, without inheriting all the other methods that you’ll never need. This is possible with the borrowing methods pattern, which benefits from the function methods  call() and apply(). // call() example…

All object members are public in JavaScript. var myobj = { myprop : 1, getProp : function() { return this.myprop; } }; console.log(myobj.myprop); // `myprop` is publicly accessible console.log(myobj.getProp()); // getProp() is public too The same is…

Commonalities • There’s a convention on how to name a method, which is to be considered the constructor of the class. • Classes inherit from other classes. • There’s access to the parent class (superclass) from within the child class. The function ta…

// the parent constructor function Parent(name) { this.name = name || 'Adam'; } // adding functionality to the prototype Parent.prototype.say = function () { return this.name; }; // empty child constructor function Child(name) {} inherit(Child, Paren…

Chaining Pattern - Call methods on an object one after the other without assigning the return values of the previous operations to variables and without having to split your calls on multiple lines. var obj = { value: 1, increment: function () { this…

MYAPP.namespace('MYAPP.utilities.array'); MYAPP.utilities.array = (function () { // dependencies var uobj = MYAPP.utilities.object, ulang = MYAPP.utilities.lang, // private properties array_string = "[object Array]", ops = Object.prototype.toStr…

7.1 Singleton The idea of the singleton pattern is to have only one instance of a specific class. This means that the second time you use the same class to create a new object, you should get the same object that was created the first time. var obj =…

Loop through arguments and copy every property of every object passed to the function. And the result will be a new object that has the properties of all the source objects. function mix() { var arg, prop, child = {}; for (arg = 0; arg < arguments.le…

Shallow copy pattern function extend(parent, child) { var i; child = child || {}; for (i in parent) { if (parent.hasOwnProperty(i)) { child[i] = parent[i]; } } return child; } Deep copy pattern function extendDeep(parent, child) { var i, toStr = Obje…

No classes involved; Objects inherit from other objects. Use an empty temporary constructor function  F().  Set the prototype of  F() to be the parent object. Return a new instance of the temporary constructor. function Object(o) { function F() {} F.…

In Java you could do something like: Person adam = new Person(); In JavaScript you would do: var adam = new Person(); JavaScript’s constructor invocation looks as if Person were a class, but it’s important to keep in mind that Person is still just a…

Advantage Avoid re-created instance method to this inside of the constructor. method() implementation The method() takes two parameters: • The name of the new method • The implementation of the method if (typeof Function.prototype.method !== "functio…

Principle Make variables shouldn't be changed stand out using all caps. Add constants as static properties to the constructor function. // constructor var Widget = function () { // implementation... }; // constants Widget.MAX_HEIGHT = 320; Widget.MAX…

Public Static Members // constructor var Gadget = function (price) { this.price = price; }; // a static method Gadget.isShiny = function () { // this always works var msg = "you bet"; // Checking if the static method is called by instance. if (t…

Drawbacks of the namespacing pattern • Reliance on a single global variable to be the application’s global. In the namespacing pattern, there is no way to have two versions of the same application or library run on the same page, because they both ne…

It’s a good idea to declare the modules your code relies on at the top of your function or module. The declaration involves creating only a local variable and pointing to the desired module. var myFunction = function() { // dependencies var event = Y…

global namespace object // global object var MYAPP = {}; // constructors MYAPP.Parent = function() { }; MYAPP.Child = function() { }; // a variable MYAPP.some_var = 1; // an object container MYAPP.modules = {}; // nested objects MYAPP.modules.module1…

Function Application apply() takes two parameters: the first one is an object to bind to this inside of the function, the second is an array or arguments, which then becomes the array-like arguments object available inside the function. If the first…

Configuration Objects Passing a large number of parameters is not convenient. A better approach is to substitute all the parameters with only one and make it an object. var conf = { username: "batman", first: "Bruce", last: "Wayne…

Gets a length property containing the number of arguments the function expects: function func(a, b, c) {} console.log(func.length); var myFunc = function () { // serialize the arguments object as a JSON string and use that string as a key in your cac…

When you know that a certain condition will not change throughout the life of the program, it makes sense to test the condition only once. Browser sniffing (or feature detection) is a typical example. // BEFORE var utils = { addListener : function(el…

Go beyond console.log by learning about log levels, filtering log output and structuring your output to be meaningful and concise. The JavaScript console object offers many methods to make your life easier - start learning them here! console.log("thi…

JSON: JavaScript Object Notation {"name": "value", "some": [1, 2, 3]}  The only syntax difference between JSON and the object literal is that property names need to be wrapped in quotes to be valid JSON. In object literals th…

Free and open source tools for doc generation: the JSDoc Toolkit (http://code.google.com/p/jsdoc-toolkit/) and YUIDoc (http://yuilibrary.com/projects/yuidoc). Process of generating API documentation • Writing specially formatted code blocks • Running…

1. Capitalizing Constructors var adam = new Person(); 2. Separating Words camel case - type the words in lowercase, only capitalizing the first letter in each word. upper camel case, as in  MyConstructor(), lower  camel  case,  as  in  myFunction(),…

Disadvantage Other developers using your code will probably expect the built-in JavaScript methods to work consistently and will not expect your additions. Properties you add to the prototype may show up in loops that don't use hasOwnProperty(), so t…

1.1 Pattern "theme of recurring events or objects… it can be a template or model which can be used to generate things" (http://en.wikipedia.org/wiki/Pattern). • Design patterns - Elements of Reusable Object-Oriented Software. • Coding patterns -…

( { // here you can define setting values // a.k.a. configuration constants maxwidth : 600, maxheight : 400, // you can also define utility methods gimmeMax : function() { return this.maxwidth + "x" + this.maxheight; }, // initialize init : func…

function writeCode(callback) { // do something... callback(); // ... } function introduceBugs() { // ... make bugs } writeCode(introduceBugs); A Callback Example // refactored findNodes() to accept a callback var findNodes = function (callback) { var…

Functions are first-class objects and they provide scope. • Can be created dynamically at runtime, during the execution of the program • Can be assigned to variables, can have their references copied to other variables, can be augmented, and, except…