Base64 - 文件已损坏

我正在尝试通过javascript上传pdf文件。我有文件的 base64 表示形式，我对其进行了解码。文件已上传，但数据似乎已损坏。

当我尝试打开文件时，错误消息显示"文件已损坏，无法修复"。

我得到 base64 字符串服务器端是这样的......

byte[] buffer = new byte[length];  
var postedFile = httpRequest.Files[file];                 
postedFile.InputStream.Read(buffer, 0, length);
string encodedString = Convert.ToBase64String(buffer);

这是我为上传文件而进行的 ajax 调用

var data= Base64.decode(result); //result is the base64 encoded string
 $.ajax({
                    url: url,
                    type: "POST",
                    data: data,
                    processData: false,
                    headers: {
                        "accept": "application/json;odata=verbose",
                        "X-RequestDigest": _digetsValue,
                        "content-length": length
                    },
                    success: function (data)
                    {
                        alert("it worked");
                    },
                    error: function (err)
                    {
                    }
                });

对于解码，我正在使用这段代码...或者从这里 如何在 JavaScript 中将字符串编码为 Base64？

var Base64 = {
        // private property
        _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
        // public method for encoding
        encode: function (input)
        {
            var output = "";
            var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
            var i = 0;
            input = Base64._utf8_encode(input);
            while (i < input.length)
            {
                chr1 = input.charCodeAt(i++);
                chr2 = input.charCodeAt(i++);
                chr3 = input.charCodeAt(i++);
                enc1 = chr1 >> 2;
                enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
                enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
                enc4 = chr3 & 63;
                if (isNaN(chr2))
                {
                    enc3 = enc4 = 64;
                } else if (isNaN(chr3))
                {
                    enc4 = 64;
                }
                output = output +
                Base64._keyStr.charAt(enc1) + Base64._keyStr.charAt(enc2) +
                Base64._keyStr.charAt(enc3) + Base64._keyStr.charAt(enc4);
            }
            return output;
        },
        // public method for decoding
        decode: function (input)
        {
            var output = "";
            var chr1, chr2, chr3;
            var enc1, enc2, enc3, enc4;
            var i = 0;
            input = input.replace(/[^A-Za-z0-9'+'/'=]/g, "");
            while (i < input.length)
            {
                enc1 = Base64._keyStr.indexOf(input.charAt(i++));
                enc2 = Base64._keyStr.indexOf(input.charAt(i++));
                enc3 = Base64._keyStr.indexOf(input.charAt(i++));
                enc4 = Base64._keyStr.indexOf(input.charAt(i++));
                chr1 = (enc1 << 2) | (enc2 >> 4);
                chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
                chr3 = ((enc3 & 3) << 6) | enc4;
                output = output + String.fromCharCode(chr1);
                if (enc3 != 64)
                {
                    output = output + String.fromCharCode(chr2);
                }
                if (enc4 != 64)
                {
                    output = output + String.fromCharCode(chr3);
                }
            }
            output = Base64._utf8_decode(output);
            return output;
        },
        // private method for UTF-8 encoding
        _utf8_encode: function (string)
        {
            string = string.replace(/'r'n/g, "'n");
            var utftext = "";
            for (var n = 0; n < string.length; n++)
            {
                var c = string.charCodeAt(n);
                if (c < 128)
                {
                    utftext += String.fromCharCode(c);
                }
                else if ((c > 127) && (c < 2048))
                {
                    utftext += String.fromCharCode((c >> 6) | 192);
                    utftext += String.fromCharCode((c & 63) | 128);
                }
                else
                {
                    utftext += String.fromCharCode((c >> 12) | 224);
                    utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                    utftext += String.fromCharCode((c & 63) | 128);
                }
            }
            return utftext;
        },
        // private method for UTF-8 decoding
        _utf8_decode: function (utftext)
        {
            var string = "";
            var i = 0;
            var c = c1 = c2 = 0;
            while (i < utftext.length)
            {
                c = utftext.charCodeAt(i);
                if (c < 128)
                {
                    string += String.fromCharCode(c);
                    i++;
                }
                else if ((c > 191) && (c < 224))
                {
                    c2 = utftext.charCodeAt(i + 1);
                    string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                    i += 2;
                }
                else
                {
                    c2 = utftext.charCodeAt(i + 1);
                    c3 = utftext.charCodeAt(i + 2);
                    string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                    i += 3;
                }
            }
            return string;
        }
    }

最初，我正在做这样的事情...

getFileBuffer = function (file)
{
    var deferred = $.Deferred();
    var reader = new FileReader();
    reader.onload = function (e)
    {
        deferred.resolve(e.target.result);
    }
    reader.onerror = function (e)
    {
        deferred.reject(e.target.error);
    }
    reader.readAsArrayBuffer(file);
    return deferred.promise();
};

但当然，这是HTML5等独有的。因此，当我调用我的 ajax 函数时，我会从文件读取器传入这个数组缓冲区，瞧！它会起作用。现在我正在尝试模仿IE8的相同功能。这可能吗？

谢谢