Create binary blob in JS

Question

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?

Answer 1

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/

Answer 2

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.