One <span> per character in web-based text editor

I'm developing a web-based text editor without any contentEditable, textarea or input things. The biggest portion of my work is to measure widths of text on the left (right) side from the current caret position a开发者_运维问答nd moving the caret in the text.

For example when user presse the DOWN key a current left-offset of the caret must be computed and on the line below a character which's position is most similar must be found.

One very convenient way to do is to use one DOM element per character - I can just look at the offsetLeft property. Also, positioning the caret is much easier. Actually, everything is easier.

However I'm very unsure about the performance implications. I have seen this technique (or similar) used on some web-based JavaScript "IDE"s and it works just fine there.

Do you have any hints, tips?

Do you know some other fast way how to measure width of text. I want to avoid putting sections of a line to a DOM element and measuring its width each time as I think it will be much slower.

EDIT: I'm mostly asking about the main fact of EXISTENCE of many dom elements. How to do the measuring is a different thing.

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I've seen this done (unfortunately can't find the link now) by using a canvas object and its measureText() method - basically you can ask a canvas "what size would this piece of text be if i rendered it in this style?" and use that to determine your caret position on the surrounding lines. This is performant, but of course it will only work in HTML5-capable browsers, and maybe not all of them.

But frankly this sounds like a big pain in the neck and probably more trouble than it's worth for an in-browser editor :)

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You might be interested in this, which is a javascript implementation of the VI text editor. Unfortunately it does use a textarea, however not in the typical manner.