Whitespace depends on the context. For example, you could have characters that are not counted as whitespace in Unicode, but end up rendering as whitespace when displayed in a particular context. The only real way to check for this is to actually try to render it and see what happens. There are some other ways to approximate it, like checking the font that you use for rendering, or the bounds of the glyph, or other things like that, but the only way to really know for sure in all cases is just to render it and see what happens.
With font.color = white even an ordinary "W" could count as whitespace...
Something to remember if you see whitespace with an extraordinary width out there in the wild...
The \s character class in JavaScript regular expressions includes 25 characters. I don’t know if that perfectly matches the Unicode list of 25 characters, but it does make identifying white space simplistic.
White space characters are challenging to differentiate in human readable text, but JavaScript makes that perfectly clear to humans by splitting a string on every character, which is helpful for debugging.
White space characters are challenging to differentiate in human readable text, but JavaScript makes that perfectly clear to humans by splitting a string on every character, which is helpful for debugging.