//获取字符串字节数

//方法一

/* */

String.prototype.getBytesLength = function () {

    var length = 0;

    for (i = 0; i < this.length; i++) {

        iCode = this.charCodeAt(i);

        if ((iCode >= 0 && iCode <= 255) || (iCode >= 0xff61 && iCode <= 0xff9f)) {

            length += 1;

        } else {

            length += 2;

        }

    }

    return length;

}

//方法二

/* */

String.prototype.getBytesLength = function () {

    return this.replace(/[^\x00-\xff]/gi, "--").length;

}

document.write("Sn杨".getBytesLength());//结果：4