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I'm generating a file client-side, I have the data in hexadecimal and just want to let the user download the generated file.

var blob = new Blob([hexData], {type: "application/octet-stream"});
console.log(URL.createObjectURL(blob));

The resulting file is a plain-text file containing hex data in ASCII. How can I force the Blob to contain the binary data as is and not as text?

user3491456
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2 Answers2

10

Derived from @Musa's solution above so I cannot take credit, but it's clearer to write this as an answer than my lame comment to his answer.

var byteArray = new Uint8Array(hexdata.match(/.{2}/g)
                              .map(e => parseInt(e, 16)));
var blob = new Blob([byteArray], {type: "application/octet-stream"});

Maybe this is easier to understand? I personally think it is clearer.

Alan Mimms
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7

Convert you data to a binary array then create a blob from that.

var byteArray = new Uint8Array(hexdata.length/2);
for (var x = 0; x < byteArray.length; x++){
    byteArray[x] = parseInt(hexdata.substr(x*2,2), 16);
}
var blob = new Blob([byteArray], {type: "application/octet-stream"});

http://jsfiddle.net/mowglisanu/15h9o3d5/

Musa
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  • I'd like to suggest a simpler and maybe cleaner (eye of the beholder) way. `var byteArray = new Uint8Array(hexdata.match(/.{2}/g) .map(e => parseInt(e, 16)));` This splits the hex data into two byte hunks, parses them as hex into numbers, then returns an array of these to the Uin8Array constructor. – Alan Mimms Jun 16 '16 at 23:08