Question

I’m screwing around with some javascript that would insert a random miscellaneous unicode symbol somewhere in a document. (like these symbols)

However, I want to make sure that I’m only inserting the generated character, if that character is not to be printed as one of those “੟” squares.

So far, I’m generating random numbers between 2600 and 2699. But I want to make sure they’re valid and not squares. Nevermind the fact that I’m not generating hex codes, just ints, it doesn’t really matter which symbols I’m missing.

String.fromCharCode(2600+(Math.floor(Math.random()*70)));

Calling this a few times would give me: “ਖ਼੕ੁ੡਴਱ੜਯ੉”

Cheers!

Answer 1

There are two fundamental things that might show as such squares (or a question mark in a lozenge, or something different entirely, e.g. the code point value in a square):

1. An illegal character that gets replaced by U+FFFD Replacement Character for display
2. A character that has no glyph in the selected font (or others that might get substituted).

For the first case you can try throwing out invalid code points (non-characters), but for the second you have little choice in the matter, as it all depends on the font, the browser, other installed fonts, the technology used to render text, etc.