Javascript switch vs. if ... else if ... else [英] Javascript switch vs. if...else if...else

问题描述

我有几个问题：

1. 在switch语句和if语句之间有Javascript的性能差异else if .... else？


2. 如果是这样，为什么？


3. 是switch的行为，如果... else if ... else不同的浏览器？ （FireFox，IE，Chrome，Opera，Safari）

提出此问题的原因似乎是switch语句大约1000s在Firefox中。

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已编辑
不幸的是，这不是我的代码。从编译库和我没有访问的代码。生成javascript的方法称为

  CreateConditionals（string name，string arrayofvalues，string arrayofActions）
  

注意arrayofvalues是逗号分隔的列表。

  function [name]（value）{
 if（value == [value from array index x]）{ 
 [从数组索引x的动作] 
} 
} 
  

注意：其中[name] =传递到serverside函数的名称

现在我改变了要插入到TextArea的函数的输出，写了一些javascript代码来解析函数并将其转换为一组案例统计。
最后我运行的函数，它运行正常，但性能不同的IE和Firefox。

解决方案

1. 通常是。


2. 查看更多信息


3. 具有不同的JS处理引擎，但是，在下面的站点上运行测试时，开关总是在大量迭代上执行if，elseif。

真正的测试网站 p>

Guys I have a couple of questions:

1. Is there a performance difference in Javascript between a switch statement and an if...else if....else?
2. If so why?
3. Is the behavior of switch and if...else if...else different across browsers? (FireFox, IE, Chrome, Opera, Safari)

The reason for asking this question is it seems that I get better performance on a switch statement with approx 1000s cases in Firefox.

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Edited Unfortuantly this is not my code the Javascript is being produced serverside from a compiled library and I have no access to the code. The method that is producing the javascript is called

CreateConditionals(string name, string arrayofvalues, string arrayofActions)

note arrayofvalues is a comma separated list.

what it produces is

function [name] (value) {
  if (value == [value from array index x]) {
     [action from array index x]
  }
}

Note: where [name] = the name passed into the serverside function

Now I changed the output of the function to be inserted into a TextArea wrote some javascript code to parse through the function and convert it to a set of case statments. finally I run the function and it runs fine but performance differs in IE and Firefox.

解决方案

Answering in generalities:

1. Yes, usually.
2. See More Info Here
3. Yes, because each has a different JS processing engine, however, in running a test on the site below, the switch always out performed the if, elseif on a large number of iterations.

Really old test site

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