Detecting individual Unicode character support with JavaScript

Question

Is it possible to detect if the client supports a particular Unicode character or if it will be rendered as a missing glyph box?

Important: Support in as many browsers as possible

Not important: Efficiency, speed, or elegance

The only method I can think of trying is using a canvas, so I figured I'd ask before I start going down that road.

Thanks!

Edit: This is not intended for use on a public web site; I am just trying to compile a list of characters supported by each browser.

Answer 1

If you want to maximize browser support, you probably don't want to rely on javascript for anything. Many mobile browsers don't even support it.

If the browser does not support a char set, what is the fall back? Displaying the content in another language? Perhaps links one the site that switch languages on demand would be more robust.

Answer 2

Since efficiency and speed do not matter, save yourself the trouble and use an image of the character instead of an HTML entity.

Answer 3

This is more of a wild idea than a real answer:

If you could find a character which you knew would always render as a missing glyph box, you could use the same technique as this javascript font detector--render the character and the missing glyph box offscreen and compare their widths. If they're different, then you know the character is not rendering as a missing glyph box. Of course, this won't work at all for fixed-width fonts, and it could have a lot of fixed negatives for other fonts where a lot of the characters are the same width.