Complete a string (number) to the specified length. Useful when you needs a formatted number as '00000123'

completeToLength.js

/**
 * Generates a string length of a specific character
 * @param char Character to repeat
 * @param times How many times
 * @returns {string}
 */
String.prototype.repeat= function(n){
    n= n || 1;
    return Array(n+1).join(this);
}
/**
 * Completes a string to specified length with the specified char
 * @param str
 * @param length
 * @param char
 * @param toRight
 * @returns {string}
 */
var completeToLength = function (str, length, char) {
    char = char || "0";
    return char.repeat(length - str.toString().length) + str;
};