simple-random/lib/simple_random.js

A simple flexible javascript library that creates random alpha-numeric strings. Works in both NodeJS and the browser.

function mathRandom(length, chars) {
    var result = "";
    var index;
    for (var i = length; i > 0; --i) {
        index = Math.round(Math.random() * (chars.length - 1));
        result += chars[index];
    }
    return result;
}

function bytesToChars(byteArray, chars) {
    var index;
    var result = "";
    for (var i = 0; i < byteArray.length; i++) {
        index = byteArray[i] % chars.length;
        result += chars[index];
    }
    return result;
}

var _digits = "0123456789";
var _letters = "abcdefghijklmnopqrstuvwxyz";

function initOptions(options) {

    //defaults
    options = options || {};
    options.length = options.length || 16;
    options.chars = options.chars || "";
    options.prefix = options.prefix || "";
    options.suffix = options.suffix || "";
    options.digits = typeof options.digits === "undefined" ? true : options.digits;
    options.letters = typeof options.letters === "undefined" ? true : options.letters;
    options.caseSensitive = typeof options.caseSensitive === "undefined" ? true : options.caseSensitive;

    if (!options.chars) {
        if (options.digits) {
            options.chars += _digits;
        }
        if (options.letters) {
            options.chars += _letters;

            if (options.caseSensitive) {
                options.chars += _letters.toUpperCase();
            }
        }

    }

    if (typeof options.secure === "undefined") {
        options.secure = false;
    }
    return options;
}

function createSimpleRandom(secureContainer) {
    return function simpleRandom(options) {
        options = initOptions(options);
        var result;
        if (options.secure) {
            var randomBytes = secureContainer.getRandomBytes(options.length);
            result = bytesToChars(randomBytes, options.chars);
        } else {
            result = mathRandom(options.length, options.chars);
        }
        return options.prefix + result + options.suffix;
    };

}

module.exports = {create: createSimpleRandom};