js怎么统计字节数

GetLength = function(str) {

    ///<summary>获得字符串实际长度，中文2，英文1</summary>
    ///<param name="str">要获得长度的字符串</param>
    var realLength = 0, len = str.length, charCode = -1;
    for (var i = 0; i < len; i++) {
        charCode = str.charCodeAt(i);
        if (charCode >= 0 && charCode <= 128)
            realLength += 1;
        else
            realLength += 2;
    }
    return realLength;

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