is there a firefox addon that provides jsFiddle like features

I just saw jsFiddle today and am wondering that is there a FireFox addon that provides jsFiddle like features. Especially when you enter the html and css, jsFiddle shows you a layout of the page. Is there any addon that shows such layout for "offline viewing"? I use Firebug but there is开发者_运维知识库n't such layout. Does somebody know about it?

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Not a firefox add-on, only in the interest of self-promotion:

I have created a Vim script with similar (but at the moment very limited) functionality: vimfiddler. Vim integrates with selenium to drive a browser. Provides a jsfiddlerish experience running locally on your own computer.

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In Google Chrome you can edit every element of the page. Just open a new tab, hit F-12 and edit to your heart's desire. Add some css or javascript to the head tags, put whatever HTML you want in the body, and you're good to go.

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This add-on sounds like what you need : https://addons.mozilla.org/en-us/firefox/addon/devtools-prototyper/?src=ss

Just install it, open the devtools, then switch to the "Prototyper" tab.