1. // 使用立即执行函数，包装一层，解决不同环境的加载问题，比如浏览器端或者node.js中的加载
    2. ( function( global, factory ) { //第一个参数为全局变量，第二未构造工厂。通过判断全局变量来确定环境。
    4.     "use strict";
    6.   // 判断是否为CommonJS规范的环境（node.js是这个规范），或者类似这个规范
    7.   // 这个规范会使用同步式的module.exports来导出模块。
    8.     if ( typeof module === "object" && typeof module.exports === "object" ) { 
    10.         // For CommonJS and CommonJS-like environments where a proper `window`
    11.         // is present, execute the factory and get jQuery.
    12.         // For environments that do not have a `window` with a `document`
    13.         // (such as Node.js), expose a factory as module.exports.
    14.         // This accentuates the need for the creation of a real `window`.
    15.         // e.g. var jQuery = require("jquery")(window);
    16.         // See ticket #14549 for more info.
    17.        // 此处注意 global传入时 全局存在 window对象时，global为window，否则为整个函数外部的的this
    18.         module.exports = global.document ?
    19.       // 如果存在document属性则执行构建工厂，并传入global对象，并标记为非全局。
    20.             factory( global, true ) :
    21.             function( w ) { // 调用说明node.js需要使用 var jQuery = require("jquery")(window);
    22.                 if ( !w.document ) { // 校验后续使用构建工厂时，是否传入了正确的对象，（多半为window）
    23.                     throw new Error( "jQuery requires a window with a document" );
    24.                 }
    25.                 return factory( w );
    26.             };
    27.     } else {
    28.     // 非 commonjs环境，直接执行构建工厂，并标记为全局
    29.         factory( global );
    30.     }
    32. } )( typeof window !== "undefined" ? window : this, // node.js下不存在window,this为global对象。node下 this === global
    33.     function( window, noGlobal ) {
    35.   var
    36.         version = "3.5.1",
    38.         // Define a local copy of jQuery
    39.         jQuery = function( selector, context ) {
    41.             // The jQuery object is actually just the init constructor 'enhanced'
    42.             // Need init if jQuery is called (just allow error to be thrown if not included)
    43.             return new jQuery.fn.init( selector, context );
    44.         };
    46.   // 其余的代码，补充jQuery功能，此处省略
    48. // Edge <= 12 - 13+, Firefox <=18 - 45+, IE 10 - 11, Safari 5.1 - 9+, iOS 6 - 9.1
    49. // throw exceptions when non-strict code (e.g., ASP.NET 4.5) accesses strict mode
    50. // arguments.callee.caller (trac-13335). But as of jQuery 3.0 (2016), strict mode should be common
    51. // enough that all such attempts are guarded in a try block.
    52.     "use strict";
    53.   // Register as a named AMD module, since jQuery can be concatenated with other
    54. // files that may use define, but not via a proper concatenation script that
    55. // understands anonymous AMD modules. A named AMD is safest and most robust
    56. // way to register. Lowercase jquery is used because AMD module names are
    57. // derived from file names, and jQuery is normally delivered in a lowercase
    58. // file name. Do this after creating the global so that if an AMD module wants
    59. // to call noConflict to hide this version of jQuery, it will work.
    61. // Note that for maximum portability, libraries that are not jQuery should
    62. // declare themselves as anonymous modules, and avoid setting a global if an
    63. // AMD loader is present. jQuery is a special case. For more information, see
    64. // https://github.com/jrburke/requirejs/wiki/Updating-existing-libraries#wiki-anon
    66.   // 检测是否为 AMD 规范
    67.     if ( typeof define === "function" && define.amd ) {
    68.         define( "jquery", [], function() {
    69.             return jQuery;
    70.         } );
    71.     }
    74.   // 执行 window.jQuery = window.$ = jQuery;之前先保存 原始的 window.jQuery和window.$;
    75.     var
    76.         // Map over jQuery in case of overwrite
    77.         _jQuery = window.jQuery, 
    79.         // Map over the $ in case of overwrite
    80.         _$ = window.$;
    82.     jQuery.noConflict = function( deep ) {
    83.         if ( window.$ === jQuery ) { 
    84.       // 如果 window.$是被jQuery自身占用，则退回原始的值。避免因为不检测而直接复原
    85.             window.$ = _$;
    86.         }
    88.     // 同理，传入deep为true，则将window.jQuery也进行检测还原
    89.         if ( deep && window.jQuery === jQuery ) {
    90.             window.jQuery = _jQuery;
    91.         }
    93.     // 同时返回jQuery对象，不然后续无法进行调用
    94.         return jQuery;
    95.     };
    97. // Expose jQuery and $ identifiers, even in AMD
    98. // (#7102#comment:10, https://github.com/jquery/jquery/pull/557)
    99. // and CommonJS for browser emulators (#13566)
    100.   // 全局则进行挂载对象到window
    101.     if ( typeof noGlobal === "undefined" ) {
    102.         window.jQuery = window.$ = jQuery;
    103.     }
    105.   // 返回jQuery对象，给common.js模块使用。
    106.   // 不然无需返回值。
    107.     return jQuery;
    108. } );