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  • JavaScript Patterns 5.4 Module Pattern

    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)

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  • 原文地址:https://www.cnblogs.com/haokaibo/p/Module-Pattern.html
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