jquery - What is the most common waste of computing power in Javascript? -

we've seen people this:

jquery('a').each(function(){     jquery(this)[0].innerhtml += ' proccessed'; });  function letspolutens() {     polute = '';     (morepolution = 0; morepolution < arguments.length; morepolution++)         polute.join(arguments[morepolution]);     return polute; } 

and on. wondering people have seen common javascript/jquery technique slowing down page and/or wasting time javascript engine.

i know question may not seem fit what's accepted question, yet i'm asking "what common accepted waste?"

i'm guilt of this. using element's class in jquery selector. instead of combining class selector elements tag name.

<div></div> <div class="hide"></div> <div class="show"></div> <div class="hide"></div> <div class="hide again"></div> 

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$(".hide").hide(); 

instead of quicker

$("div.hide").hide() 

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also inefficient, many people don't make use of context parameter selectors

$( selector, [ context ] )

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   $("#mydiv").click(function () {       $("#mydiv span").show();    } 

which can handled better this:

   $("#mydiv").click(function () {       $("span", this).show();    }