什么是“var _gaq = _gaq ||” []; "对于？ [英] What is "var _gaq = _gaq || []; " for?

问题描述

Google Analytics中的异步跟踪代码如下所示：

  var _gaq = _gaq || []; 
 _gaq.push（['_ setAccount'，'UA-XXXXX-X']）; 
 _gaq.push（['_ trackPageview']）; 
 
（function（）{
 var ga = document.createElement（'script'）; ga.type ='text / javascript'; ga.async = true; 
 ga .src =（'https：'== document.location.protocol？'https：// ssl'：'http：// www'）+'.google-analytics.com / ga.js'; 
 var s = document.getElementsByTagName（'script'）[0]; s.parentNode.insertBefore（ga，s）; 
}）（）; 
  

关于第一行：

  var _gaq = _gaq || []; 
  

我认为如果 _gaq 是已经定义我们应该使用它，否则我们应该是一个数组。

另外，如果是否有关系？ _gaq 被重命名？换句话说，Google Analytics是否依赖名为 _gaq ？

解决方案

的全局对象。

是的，它确保定义 _gaq ，所以 _gaq.push（）永远不会失败。 p>

我不会在GA代码中弄乱变量的名字......你有什么理由要这样做吗？它与你的任何变量有冲突吗？ （然后我会改变我的...）

The Async Tracking code in Google Analytics looks like this:

var _gaq = _gaq || []; 
_gaq.push(['_setAccount', 'UA-XXXXX-X']); 
_gaq.push(['_trackPageview']); 

(function() { 
  var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; 
  ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; 
  var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); 
})(); 

About The first line:

var _gaq = _gaq || []; 

I think it ensures that if _gaq is already defined we should use it otherwise we should an array.

Can anybody explain what this is for?

Also, does it matter if _gaq gets renamed? In other words, does Google Analytics rely on a global object named _gaq?

解决方案

Yes, it ensures that _gaq is defined, so that _gaq.push() never fails.

I would not mess with the name of the variables in GA's code... do you have any reason to? Does it conflict with any of your variables? (Then I would change mine...)

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