javascript全局变量封装模块实现代码

时间：2021-05-26

下面的代码是我的测试代码，注释很重要：
复制代码 代码如下:

/** Enable ECMAScript "strict" operation for this function. See more:
* http://ejohn.org/blog/ecmascript-5-strict-mode-json-and-more/
* http://stackoverflow.com/questions/5020479/what-advantages-does-using-functionwindow-document-undefined-windo
* Q1: Why are window and document being fed instead of just being accessed normally?
* A1: Generally to fasten the identifier resolution process, having them as local variables can help (although IMO the performance improvements may be negligible).
* A2: Passing the global object is also a widely used technique on non-browser environments, where you don't have a window identifier at the global scope, e.g.:
* (function (global) {
* //..
* })(this); // this on the global execution context is the global object itself
* A3: Passing window and document allows the script to be more efficiently minified
*
* Q2: Why the heck is undefined being passed in?
* A1: This is made because the undefined global property in ECMAScript 3, is mutable, meaning that someone could change its value affecting your code, for example:
* undefined = true; // mutable
* (function (undefined) {
* alert(typeof undefined); // "undefined", the local identifier
* })(); // <-- no value passed, undefined by default
* If you look carefully undefined is actually not being passed (there's no argument on the function call),
* that's one of the reliable ways to get the undefined value, without using the property window.undefined.
*
*/
(function(window, document, undefined) {
"use strict";
window.test = {
init: function () {
"use strict";
alert("ok");
}
};
})(window, document);// no undefined parameter here to avoid using mutable window.undefined changed by other guy

1.说明，参考了一篇文章和stackoverflow上的一个帖子
2.(function(){})() 这种代码写在独立的js文件里，当js文件被html加载的时候，该函数就会执行。实际上创建了windows.text对象。
以后html代码就可用test.init的形式调用方法。
测试html部分代码如下：
复制代码 代码如下:
[plain] view plaincopyprint?
<head>
<title>AppEngine SDK</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="../../master/script/third_party/jquery-1.8.0.min.js"></script>
<script type="text/javascript" src="../../master/plugin/jquery-validation-1.9.0/jquery.validate.js"></script>
<script type="text/javascript" src="../../master/plugin/artDialog4.1.6/jquery.artDialog.js"></script>
<script type="text/javascript" src="../../master/script/app/test.js"></script>
<script type="text/javascript">
$(document).ready(function() {
test.init();
})
</script>
</head>

3.Jslint会报两个问题，一是关于undefined的，没找到什么好方法，任它抱怨吧。另一格式最后调用方式要改成：
复制代码 代码如下:
[javascript] view plaincopyprint?}(window, document)); }(window, document));

无所谓了，就任由它吧。只要功能正常就行。

声明：本页内容来源网络，仅供用户参考；我单位不保证亦不表示资料全面及准确无误，也不保证亦不表示这些资料为最新信息，如因任何原因，本网内容或者用户因倚赖本网内容造成任何损失或损害，我单位将不会负任何法律责任。如涉及版权问题，请提交至online#300.cn邮箱联系删除。

相关文章