So, I was wondering if the following is possible..

I want to use MathML or maybe javascript graphics and essentially create a real-time math preview. So I want to have a text box where you insert your source code, and I want the preview box to update automatically.

For example, say I want the preview box to refresh every time the user enters a space character. Is there a way to get only the new source code entered to render in the preview box without having to re-render the entire preview every time?

For example, if a user types 2x^3, I want the math equivalent to show up in the preview window. If a user then types in " + 2x" I want just the " + 2x" part to be drawn right next to the already-drawn "2x^3".

Is this possible? Or is the only way to re-render the entire preview every time the user types in a new term? I would like to only change what the user has edited. If a user edits the middle of the math, then I have no choice and have to re-render everything after what the user has just edited, but when the user is editing the math at the very end, can I not just tag it on to the end and render just that little piece?