Generate a random string using Javascript

generate-random-string.js

/**
 * Generates random string
 * @param length
 * @returns {string}
 */
function generateRandomString(length) {
    var characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    length = typeof length == 'undefined' ? 16 : length;

    var rndCharIndex, rndStr = "";
    for (var i = 1; i <= length; i++) {
        rndCharIndex = Math.floor(Math.random() * characters.length);
        rndStr += characters.charAt(rndCharIndex);
    }

    return rndStr;
}