问题
Is there a way in JavaScript/CSS/web stuff to detect whether the system has a valid glyph for a certain Unicode character?
For example, I would like to detect whether a certain character in a language shows up as a square box because the user doesn't have a font that shows those Unicode points, or if they will actually be seeing the characters.
来源：https://stackoverflow.com/questions/13639734/detect-what-unicode-glyphs-exist