Display DOM node in multiple places w/o cloning/copying
To be honest, after reading the question I almost left thinking it belongs in the "too-hard-basket", but after some thought perhaps I have some ideas.
This is a really difficult problem and the more I think about it the more I realise that there is no real way to escape needing to clone. You're right in that you can create an SVG or Canvas but it won't look the same, though with a fair amount of effort I'm sure you can get quite close but not sure how efficient it will be. You could render the HTML server-side, take a snapshot and send the image to the client but that's definitely not scalable.
The only suggestions I can think of are as follows, sorry if they are long-winded:
- How are you doing this clone? If you're going through each element and as you go through each you are creating a clone and copying the attributes one by one then this is heaavvvyy. I would strongly suggest using jQuery clone as my guess is that it's more efficient than your solution. Also, when you are making structural changes it might be useful to take advantage of jQuery's detach/remove (native JS: removeChild()) methods as this will take the element out of the DOM so you can alter it before reinserting.
- I'm not sure how you'v got your WYSIWYG, but avoid using inputs as they are heavy. If you must then I'm assuming they don't look like inputs so just swap them out with another element and style (CSS) to match. Make sure you do these swaps before you reinsert the clone in to the DOM.
- Don't literally put video at the time of showing the user comparisions. The last thing we want to do is inject 3rd party objects in to the page. Use an image, you only have to do it while comparing. Once again, do the swap before inserting the clone in to the DOM.
- I'm assuming the cloned elements won't have javascript attached to them (if there is then remove it, less moving parts is more efficiency). However, the "changed" elements will probably have some JS events attached so perhaps remove them for the period of comparision.
- Use Chrome/FF repaint/reflow tools to see how your page is working when you restructure the DOM. This is important because you could be doing some "awesome" animations that are costing you intense resources. See http://paulirish.com/2011/viewing-chromes-paint-cycle/
- Use CSS over inline styling where possible as modern browsers are optimised to handle CSS documents
- Can you make it so your users use a fast modern browser like Chrome? If it's internal then might be worth it.
- Can you do these things in Silverlight or Adobe Air? These objects get special resource privileges, so this will most likely solve your problem (according to what I'm imagining the depth of the problem is)
- This one is a bit left-field but could you open in another window? Modern browsers like Chrome will run the other window in its own process which may help.
No doubt you've probably looked in to these things more than I but good luck with it. Would be curious how you solved it.
Take a look at CSS background elements. They allow you to display DOM nodes elsewhere/repeatedly. They are of course they are read-only, but should update live.
You may still have to come up with a lot of magic around them, but it is a similar solution to:
- Create static representations of the versions with Canvas elements or something.
CSS background elements are also very experimental, so you may not get very far with them if you have to support a range of browsers.