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.toString; // private methods // ... // end var // optionally one-time init procedures // ... // public API return { inArray: function (needle, haystack) { for (var i = 0, max = haystack.length; i < max; i += 1) { if (haystack[i] === needle) { return true; } } }, isArray: function (a) { return ops.call(a) === array_string; } // ... more methods and properties }; }());
Revealing Module Pattern
Privacy pattern
The above can become:
MYAPP.utilities.array = (function () { // private properties var array_string = "[object Array]", ops = Object.prototype.toString, // private methods inArray = function (haystack, needle) { for (var i = 0, max = haystack.length; i < max; i += 1) { if (haystack[i] === needle) { return i; } } return−1; }, isArray = function (a) { return ops.call(a) === array_string; }; // end var // revealing public API return { isArray: isArray, indexOf: inArray }; }());
Modules That Create Constructors
The only difference is that the immediate function that wraps the module will return a function at the end, and not an object.
MYAPP.namespace(‘MYAPP.utilities.Array‘); MYAPP.utilities.Array = (function () { // dependencies var uobj = MYAPP.utilities.object, ulang = MYAPP.utilities.lang, // private properties and methods... Constr; // end var // optionally one-time init procedures // ... // public API -- constructor Constr = function (o) { this.elements = this.toArray(o); }; // public API -- prototype Constr.prototype = { constructor: MYAPP.utilities.Array, version: "2.0", toArray: function (obj) { for (var i = 0, a = [], len = obj.length; i < len; i += 1) { a[i] = obj[i]; } return a; } }; // return the constructor // to be assigned to the new namespace return Constr; }()); var arr = new MYAPP.utilities.Array(obj);
Importing Globals into a Module
In a common variation of the pattern, you can pass arguments to the immediate function that wraps the module. You can pass any values, but usually these are references to global variables and even the global object itself. Importing globals helps speed up the global symbol resolution inside the immediate function, because the imported variables become locals for the function.
MYAPP.utilities.module = (function (app, global) { // references to the global object // and to the global app namespace object // are now localized }(MYAPP, this));
References:
JavaScript Patterns - by Stoyan Stefanov (O`Reilly)