StringMethods

String.prototype.startsWith = function(stringValue) {
    var value = this;
    var stringToCompare = value.substr(0, stringValue.length);

    var stringStartsWith = (stringToCompare == stringValue);

    return stringStartsWith;
};

String.prototype.endsWith = function(stringValue) {
    var value = this;
    var stringToCompare = value.substr(value.length - stringValue.length);

    var stringEndsWith = (stringToCompare == stringValue);

    return stringEndsWith;
};

String.prototype.left = function(count) {
    var value = this;
    var charNumber = Number(count);
    var outputString;

    if (charNumber >= value.length) {
        outputString = value.toString();
    } else {
        outputString = value.substr(0, charNumber);
    }

    return outputString;
};

String.prototype.right = function(count) {
    var value = this;
    var charNumber = Number(count);
    var outputString;

    if (charNumber >= value.length) {
        outputString = value.toString();
    } else {
        outputString = value.substr(value.length - charNumber);
    }

    return outputString;
};

String.prototype.padLeft = function() {
    var value = this;
    var numberOfIndentations = Number(arguments[0]);
    var charToIndent;

    if (arguments[1] == undefined) {
        charToIndent = ' ';
    } else {
        charToIndent = arguments[1];
    }

    var output = new Array(numberOfIndentations + 1)
        .join(charToIndent)
        .concat(value);

    return output;
};

String.prototype.padRight = function() {
    var value = this;
    var numberOfIndentations = Number(arguments[0]);
    var charToIndent;

    if (arguments[1] == undefined) {
        charToIndent = ' ';
    } else {
        charToIndent = arguments[1];
    }

    var output = value.concat(
        new Array(numberOfIndentations + 1).join(charToIndent)
    );

    return output;
};

String.prototype.repeat = function(count) {
    var value = this;
    var numberOfRepeats = Number(count);
    var output = new Array(numberOfRepeats + 1).join(value);
    return output;
};