That would be difficult to implement in javascript, I think. Once you zoom in far enough using a float/double doesn't give you enough precision to calculate each pixel accurately. The typical solution is to switch to some sort of bignum library. That's going to be really slow in javascript.
In general though, infinite zoom mandelbrot programs do exist (don't know of any off the top of my head though), they're just trickier to implement.
In general though, infinite zoom mandelbrot programs do exist (don't know of any off the top of my head though), they're just trickier to implement.