Check if a single character is a whitespace?

Question

What is the best way to check if a single character is a whitespace?

I know how to check this through a regex.

But I am not sure if this is the best way if I only have a single character.

Isn't there a better way (concerning performance) for checking if it's a whitespace?

If I do something like this. I would miss white spaces like tabs I guess?

if (ch == ' ') {     ... } 

Answer 1

If you only want to test for certain whitespace characters, do so manually, otherwise, use a regular expression, ie

/\s/.test(ch) 

Keep in mind that different browsers match different characters, eg in Firefox, \s is equivalent to (source)

[ \f\n\r\t\v\u00A0\u2028\u2029] 

whereas in Internet Explorer, it should be (source)

[ \f\n\r\t\v] 

The MSDN page actually forgot the space ;)

Answer 2

The regex approach is a solid way to go. But here's what I do when I'm lazy and forget the proper regex syntax:

str.trim() === '' ? alert('just whitespace') : alert('not whitespace');