String.prototype javascript

String.prototype.PadLeft = function (nLen, sPad) {
    if (typeof sPad !== "string") sPad = " ";
    if (typeof nLen !== "number") nLen = 2;
    var sResult = this;
    while (sResult.length < nLen) sResult = sPad + sResult;
    return sResult;
};
String.prototype.PadRight = function(sPad, nLen) {
    if (typeof sPad !== "string") sPad = " ";
    if (typeof nLen !== "number") nLen = 2;
    var sResult = this;
    while (sResult.length < nLen) sResult += sPad;
    return sResult;
};
String.prototype.Trim = function () {
    return this.replace(/^\s+|\s+$/g, "");
};
String.prototype.TrimLeft = function () {
    return this.replace(/^\s+/, "");
};
String.prototype.TrimRight = function () {
    return this.replace(/\s+$/, "");
};