一个极为简单的requirejs实现方法

//标记已经加载成功的个数var REQ_TOTAL = 0;//模块导出window.exports = {};//记录各个模块的顺序var exp_arr = [];//判断是否数组function isArray(param) {  return param instanceof Array;}//require 真正实现function require(arr, callback) {  var req_list;  if(isArray(arr)) {    req_list = arr;  } else {    req_list = [arr];  }  var req_len = req_list.length;  //模块逐个加载  for(var i=0;i<req_len;i++) {    var req_item = req_list[i];    var $script = createScript(req_item, i);    var $node = document.querySelector('head');    (function($script) {      //检测script 的onload事件      $script.onload = function() {        REQ_TOTAL++;        var script_index = $script.getAttribute('index');        exp_arr[script_index] = exports;        window.exports = {};        //所有链接加载成功后，执行callback        if(REQ_TOTAL == req_len) {          callback && callback.apply(exports, exp_arr);               }      }      $node.appendChild($script);    })($script);  }}//创建一个script标签function createScript(src, index) {  var $script = document.createElement('script');  $script.setAttribute('src', src);  $script.setAttribute('index', index);  return $script;}

exports.define = {  topic: 'my export',  desc: 'this is other way to define ',  sayHello: function() {    console.log('topic ' + this.topic + this.desc);  }}

exports.define = {  name: 'xm',  age: 22,  info: function() {    console.log('topic ' + this.name + this.age);  }}

//测试demo require(['../res/define.js', '../res/define2.js'], function(def, def2) {   def.define.sayHello();    def2.define.info(); });