How can I check for an empty/undefined/null string in JavaScript?

Question

I saw this question, but I didn\'t see a JavaScript specific example. Is there a simple string.Empty available in JavaScript, or is it just a case of checking f

Answer 1

For checking if a string is empty, null or undefined I use:

function isEmpty(str) {
    return (!str || 0 === str.length);
}

For checking if a string is blank, null or undefined I use:

function isBlank(str) {
    return (!str || /^\s*$/.test(str));
}

For checking if a string is blank or contains only white-space:

String.prototype.isEmpty = function() {
    return (this.length === 0 || !this.trim());
};