JavaScript 检测字符串的真实长度

function(str){
    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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