在jQuery核心源代码中传递未定义的参数
问题描述：
我注意到在jQuery核心中，传入的两个参数之一是未定义的。
I noticed that in the jQuery core, one of the two arguments passed in is undefined.
(function( window, undefined ) {
// Use the correct document accordingly with window argument (sandbox)
var document = window.document;
var jQuery = (function() {
// ...defintion of the rest of the core...
window.jQuery = window.$ = jQuery;
})(window);
任何人都可以解释为什么第二个参数是 undefined ？
Can anyone explain why the second argument is undefined?
提前致谢！
答
因为有人可以像这样覆盖未定义
Since someone could overwrite undefined like this
undefined = true;
你的直接函数的代码将按原样传递（保持未定义）。我认为它在我从jQuery Source中学到的10件事。
Code of your immediate function will pass it as it should be (stay undefined). I think it's mentioned in 10 Things I Learned from the jQuery Source.