Javascript adding zeros to the beginning of a string (max length 4 chars)

Question

var number = 1310;

should be left alone.

var number = 120;

should be changed to \"0120\";

var num         


        

Answer 1

//to: 0 - to left, 1 - to right
String.prototype.pad = function(_char, len, to) {
    if (!this || !_char || this.length >= len) {
        return this;
    }
    to = to || 0;

    var ret = this;

    var max = (len - this.length)/_char.length + 1;
    while (--max) {
        ret = (to) ? ret + _char : _char + ret;
    }

    return ret;
};

Usage:

someString.pad(neededChars, neededLength)

Example:

'332'.pad('0', 6); //'000332'
'332'.pad('0', 6, 1); //'332000'