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> **Possible Duplicate:**  
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> [Determine whether element has fixed or percentage width using JavaScript](https://stackoverflow.com/questions/1782566/determine-whether-element-has-fixed-or-percentage-width-using-javascript) 
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I need to know if an element has a fluid width or not. I can go into the hairy details of why if it's really needed, but I dont think it is.

Basically, is the element `N%` width or `Npx|pt|em|etc` width? Right now I only see ways to get the current computed width. So, even if an element is 100% wide, getting the value in JS returns, like, `500px` or however wide it is at that moment.

Are there any hacks or JS API's I dont know about to know this or to get the original CSS value?

Also, please no jQuery. This is for a [JS library](http://epiceditor.com) of mine.