How can I check if string contains characters & whitespace, not just whitespace?

Instead of checking the entire string to see if there's only whitespace, just check to see if there's at least one character of non whitespace:

if (/\S/.test(myString)) {
    // string is not empty and not just whitespace
}

if (/^\s+$/.test(myString))
{
      //string contains only whitespace
}

this checks for 1 or more whitespace characters, if you it to also match an empty string then replace + with *.

Just check the string against this regex:

if(mystring.match(/^\s+$/) === null) {
    alert("String is good");
} else {
    alert("String contains only whitespace");
}

if (!myString.replace(/^\s+|\s+$/g,""))
  alert('string is only whitespace');

I've used the following method to detect if a string contains only whitespace. It also matches empty strings.

if (/^\s*$/.test(myStr)) {
  // the string contains only whitespace
}

This can be fast solution

return input < "\u0020" + 1;