[問題] undefined 改變值
js 的 undefined 是全域變數,但非保留字,所以可以改變值,不過書上寫「千萬
別這麼做」。我試著改變他的值,但也看不出有什麼影響,例如
var a;
var undefined = "aa";
alert(typeof a); // 一樣顯示 undefined
以我的功力是看不出改 undefined 有什麼用處,但這個網頁:
http://www.cnblogs.com/leadzen/archive/2009/02/18/1387750.html
留言 43 樓表示 jquery 的結構可確保 undefined 不是被惡意修改過的值。
想請教高手,惡意修改 undefined 可以做什麼事呢?
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