function(window|function(window, undefined)的意义

var num = 10000 for (var i = 0; i++; i < num) { eval("pp" + i + "=" + i); }(function(window, undefined){ var a1 = new Date(); for (var i = 0; i < num; i++) { document.write(window["pp" + i]); } var a2 = new Date(); alert(a2.getTime() - a1.getTime()); })(window); (function(undefined){ var a1 = new Date(); for (var i = 0; i < num; i++) { document.write(window["pp" + i]); } var a2 = new Date(); alert(a2.getTime() - a1.getTime()); })();

速度提升2/3
【function(window|function(window, undefined)的意义】来自:http://blog.csdn.net/qq1119753812/article/details/6820697
PS:在一间屋子里找一个杯子,和在茶几上找一个杯子;

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