Re: Performance question

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From	Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups	comp.lang.javascript
Subject	Re: Performance question
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Date	Sun, 30 Aug 2015 22:21:35 +0200
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Thomas 'PointedEars' Lahn wrote:

> Stefan Ram wrote:
>> "Joey@still_Learning.invalid" <Joey@still_Learning.invalid> writes:
>>>                                      If I declare a global variable
>>>as 'var xxx = document.getElementById('id'),' and use it throughout
>>>the script as 'xxx.value or xxx.checked,' does this improve
>>>performance?
>> 
>>   One does indeed expect such an improvement, but the
>>   best thing is to measure it under different browsers.
> 
> There is no good reason to believe that omitting a function call in favor
> of a variable access would not improve performance.  It is unnecessary to
> measure this.

Also, the variable may be declared, but the reference to the object should 
be passed to functions and methods by parameter, which should be accessed 
instead.  This shortens the effective scope chain and improves performance 
again.

The module pattern even removes the need for the variable to be declared 
global.

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
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Performance question "Joey@still_Learning.invalid" <Joey@still_Learning.invalid> - 2015-08-29 16:11 -0700
  Re: Performance question "Joey@still_Learning.invalid" <Joey@still_Learning.invalid> - 2015-08-30 09:50 -0700
  Re: Performance question Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-08-30 22:16 +0200
    Re: Performance question Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-08-30 22:21 +0200

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