JS字符串函数扩展

/****************************************************
*CreateBy:joe zhou
*CreateDate:2011-9-4
*Description:字符串辅助函数
****************************************************/
//String.prototype = {
//    caption: function () {

//    },
//    leftPad: function (padChar, width) {
//        if (this.length >= width) {
//            return this;
//        }
//    }
//};

String.prototype.padLeft = function (padChar, width) {
    var ret = this;
    while (ret.length < width) {
        if (ret.length + padChar.length < width) {
            ret = padChar + ret;
        }
        else {
            ret = padChar.substring(0, width-ret.length) + ret;
        }
    }
    return ret;
};

String.prototype.padRight = function (padChar, width) {
    var ret = this;
    while (ret.length < width) {
        if (ret.length + padChar.length < width) {
            ret += padChar;
        }
        else {
            ret += padChar.substring(0, width - ret.length);
        }
    }
    return ret;
};

String.prototype.trim = function () {
    return this.replace(/^\s+/, '').replace(/\s+$/, '');
};

String.prototype.trimLeft = function () {
    return this.replace(/^\s+/, '');
};

String.prototype.trimRight = function () {
    return this.replace(/\s+$/, '');
};

String.prototype.caption = function () {
    if (this) {
        return this.charAt(0).toUpperCase() + this.substr(1);
    }
    return this;
};

String.prototype.reverse = function () {
    var ret = '';
    for (var i = this.length - 1; i >= 0; i--) {
        ret += this.charAt(i);
    }
    return ret;
};

String.prototype.startWith = function (compareValue, ignoreCase) {
    if (ignoreCase) {
        return this.toLowerCase().indexOf(compareValue.toLowerCase()) == 0;
    }
    return this.indexOf(compareValue) == 0
};

String.prototype.endWith = function (compareValue, ignoreCase) {
    if (ignoreCase) {
        return this.toLowerCase().lastIndexOf(compareValue.toLowerCase()) == this.length - compareValue.length;
    }
    return this.lastIndexOf(compareValue) == this.length - compareValue.length;
};