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 onl

Answer 1

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');

Answer 2

function hasWhiteSpace(s) {
  return /\s/g.test(s);
}

This will work

or you can also use this indexOf():

function hasWhiteSpace(s) {
  return s.indexOf(' ') >= 0;
}

Answer 3

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 4

how about this one : ((1L << ch) & ((ch - 64) >> 31) & 0x100002600L) != 0L

Answer 5

var testWhite = (x) {
    var white = new RegExp(/^\s$/);
    return white.test(x.charAt(0));
};

This small function will allow you to enter a string of variable length as an argument and it will report "true" if the first character is white space or "false" otherwise. You can easily put any character from a string into the function using the indexOf or charAt methods. Examples:

var str = "Today I wish I were not in Afghanistan.";
testWhite(str.charAt(9));  // This would test character "i" and would return false.
testWhite(str.charAt(str.indexOf("I") + 1));  // This would return true.

Answer 6

I have referenced the set of whitespace characters matched by PHP's trim function without shame (minus the null byte, I have no idea how well browsers will handle that).

if (' \t\n\r\v'.indexOf(ch) > -1) {
    // ...
}

This looks like premature optimization to me though.