用new function(){}构造对象，而用(function(){})()调用函数-性能? [英] Constructing object with new function(){} vs. invoking function with (function(){})() - Performance?

问题描述

具有小写字母"f"的new function()`；在JavaScript中

我的直觉说，使用new关键字会比较慢.使用这两种方法有什么明显的好处?

My intuition says using the new keyword would be slower. Is there any noticeable benefit to using either method?

推荐答案

我的猜测是，函数构造函数形式(new function() { })比在闭包((function(){ return {}; })())中返回对象常量要快，因为后者似乎要比前者做更多的工作.

My guess would be that the function constructor form (new function() { }) would be faster than returning an object literal in a closure ((function(){ return {}; })()) because the latter seems to be doing a little more work than the former.

但是，看来我是错的，至少对于一些现代JavaScript引擎而言. 此jsPerf比较显示，文字/关闭形式在这两种方式中都快得多Chrome和Firefox.

However, it appears I am wrong, at least for a couple modern JavaScript engines. This jsPerf comparison shows the literal/closure form to be considerably faster in both Chrome and Firefox.

最终，我认为代码的正确性和程序员意图的清晰性比这种琐碎的优化(无论如何在现实世界中的JavaScript引擎之间可能会有很大的差异)更为重要.

Ultimately, I think the correctness of the code and the clarity of the intent of the programmer is more important than such a trivial optimization (which likely varies greatly between real-world JavaScript engines anyway).

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