Use closure to store some private data, which is accessible by the returned function but not to the outside code. var setup = function () { var count = 0; return function () { return (count += 1); }; }; // usage var next = setup(); next(); // returns…

The immediate function pattern is a syntax that enables you to execute a function as soon as it is defined. (function () { alert('watch out!'); }());  • You define a function using a function expression. (A function declaration won’t work.) • You add…

If you create a new function and assign it to the same variable that already holds another function, you’re overwriting the old function with the new one. var scareMe = function () { alert("Boo!"); scareMe = function () { alert("Double boo!…

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…

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…

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…