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…

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 =…

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…

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…

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…

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…

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…

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…

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…

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.…