LaTeX editing?

About the feasibility of supporting editing LaTeX, as you can do in MathQuill using javascript. Is this infeasibly large or potentially doable in future?

My initial thinking is that the main requirements would be, perhaps in order of difficulty:
- Need to maintain a caret position within the LaTeX string and know its coordinates and height
- When an arrow key is entered, need to move the cursor to the right position
- Open and close bracket functionality, with MathQuill's default being good: opening a bracket also creates a grey close bracket and typing close bracket in between closes the bracket.
- Appropriate actions on Delete (appropriate block to delete), function completion (e,g. sin to \sin), ^ (add ^{b} where b is some box), character typed just before box replaces box........