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JavaScript readAsBinaryString Function on E11

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攒了一身酷
攒了一身酷 2020-12-23 18:35

In this page http://www.html5rocks.com/en/tutorials/file/dndfiles/ if you scroll down to example \"Example: Slicing a file. Try it!\" you will see uses of readAsBin

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6条回答
  • 我寻月下人不归
    2020-12-23 18:53

    I combine @Jack answer with my comment to show a complete working example.

    In the <head> section I added this script to add FileReader.readAsBinaryString function in IE11

    if (FileReader.prototype.readAsBinaryString === undefined) {
    FileReader.prototype.readAsBinaryString = function (fileData) {
        var binary = "";
        var pt = this;
        var reader = new FileReader();
        reader.onload = function (e) {
            var bytes = new Uint8Array(reader.result);
            var length = bytes.byteLength;
            for (var i = 0; i < length; i++) {
                binary += String.fromCharCode(bytes[i]);
            }
            //pt.result  - readonly so assign content to another property
            pt.content = binary;
            pt.onload(); // thanks to @Denis comment
        }
        reader.readAsArrayBuffer(fileData);
    }
}

    Then I needed to slightly modify my original script code because target.result has no value when using this fallback function.

    var reader = new FileReader();
reader.onload = function (e) {
    // ADDED CODE
    if (!e) {
        var data = reader.content;
    }
    else {
        var data = e.target.result;
    }

    // business code
};
reader.readAsBinaryString(myFile);
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  • 没有蜡笔的小新
    2020-12-23 18:53

    I had some problems with the answers here and ended up making a few slight changes.

    Instead of assigning to pt.content, my solution is to send a custom object to the prototype's onload, that receiver can specifically look for, I named this property msieContent so it will be very specific.

    Also I used other accepted answer for converting Uint8Array to string in more robust way, you can see full details of it here: https://stackoverflow.com/a/12713326/213050

    Polyfill

    if (FileReader.prototype.readAsBinaryString === undefined) {
    // https://stackoverflow.com/a/12713326/213050
    function Uint8ToString(u8a: Uint8Array) {
        const CHUNK_SZ = 0x8000;
        let c = [];
        for (let i = 0; i < u8a.length; i += CHUNK_SZ) {
            c.push(String.fromCharCode.apply(null, u8a.subarray(i, i + CHUNK_SZ)));
        }
        return c.join('');
    }
    FileReader.prototype.readAsBinaryString = function (fileData) {
        const reader = new FileReader();
        reader.onload = () => this.onload({
            msieContent: Uint8ToString(new Uint8Array(<any>reader.result))
        });
        reader.readAsArrayBuffer(fileData);
    }
}

    Usage

    private _handleTextFile(file: File) {
    const reader = new FileReader();

    reader.onload = (e) => {
        // support for msie, see polyfills.ts
        const readResult: string = (<any>e).msieContent || <string>e.target.result;

    };

    reader.readAsBinaryString(file);
}
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  • 遥遥无期
    2020-12-23 18:59

    Replace 

    reader.readAsBinaryString(blob);

    with:

    reader.readAsText(blob);

    it's works well in cross browser.

    0 讨论(0)
  • Happy的楠姐
    2020-12-23 19:13

    This is my solution.

    var reader = new FileReader();
reader.readAsBinaryString(fileData);
reader.onload = function(e) {
  if (reader.result) reader.content = reader.result;
  var base64Data = btoa(reader.content);
  //...
}
//extend FileReader
if (!FileReader.prototype.readAsBinaryString) {
    FileReader.prototype.readAsBinaryString = function (fileData) {
       var binary = "";
       var pt = this;
       var reader = new FileReader();      
       reader.onload = function (e) {
           var bytes = new Uint8Array(reader.result);
           var length = bytes.byteLength;
           for (var i = 0; i < length; i++) {
               binary += String.fromCharCode(bytes[i]);
           }
        //pt.result  - readonly so assign binary
        pt.content = binary;
        $(pt).trigger('onload');
    }
    reader.readAsArrayBuffer(fileData);
    }
}
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  • 無奈伤痛
    2020-12-23 19:14

    For IE 11 you can use this XHR trick:

    function blobToBinaryStringIE11(blob) {
    var blobURL = URL.createObjectURL(blob);
    var xhr = new XMLHttpRequest;
    xhr.open("get", blobURL);
    xhr.overrideMimeType("text/plain; charset=x-user-defined");
    xhr.onload = function () {
        var binary = xhr.response;
        // do stuff
    };
    xhr.send();
}

    It's 20x faster than the Uint8Array + fromCharCode route and as fast as readAsBinaryString.

    0 讨论(0)
  • 灰色年华
    2020-12-23 19:15

    FileReader.readAsBinaryString is a non-standard function and has been deprecated.

    FileReader.readAsArrayBuffer should be used instead.

    MDN

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