How to base64 encode a raw PDF content (bytes) in JAVASCRIPT?

Question

I need to base64 encode the content of a raw PDF (already got the raw content). but i don't know why, but btoa() expect the input to be an ASCII char composed string.

btoa('ééééééé');
>> InvalidCharacterError: String contains an invalid character

Is there any way to convert raw bytes to base64 in javascript without recoding the base64 algo ? (by the way, working for images, and whatever file content)

By advance, Thanks for your answers !

[ enter image description here

I don't want to display the content, i want to base64 encode it, in order to send the encoded content on severals microservices — w2d
– w2d, Commented Dec 4, 2018 at 9:54
Georg wants to know how you read/load the raw content? This is why the complete code snippet will be very useful. Or, at least, tell us how you store bytes (for example, as ArrayBuffer or Blob)? — Victor
– Victor, Commented Dec 4, 2018 at 10:53
I store (uncasted input) the content in utf8 string buffer. I also tried in a blob, unsuccessfully. Here is a part of my input : ��D��A�-�z�� A�D<-�z��eB�B�E � ``` import base64 print(base64.b64encode("��D��A�-�z�� A�D<-�z��eB�B�E �")) # result should be 77+977+9RO+/ve+/vUHvv70t77+9eu+/ve+/vSBB77+9RDwt77+9eu+/ve+/vWVC77+9Qu+/vUUg77+9``` (modifié) — w2d
– w2d, Commented Dec 4, 2018 at 13:09

Victor · Accepted Answer · 2018-12-05 12:52:13Z

3

If you are storing contents as Blob, use the FileReader object to convert it to data URI, then remove its prefix:

var reader = new FileReader();
reader.onload = function () {
  var b64 = reader.result.replace(/^data:.+;base64,/, '');
  console.log(b64);
};
reader.readAsDataURL(your_blob);

Another way, if you are storing it as ArrayBuffer:

// Create a Uint8Array from ArrayBuffer
var codes = new Uint8Array(your_buffer);

// Get binary string from UTF-16 code units
var bin = String.fromCharCode.apply(null, codes);

// Convert binary to Base64
var b64 = btoa(bin);
console.log(b64);

answered Dec 5, 2018 at 12:52

Victor

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2 Comments

w2d Over a year ago

Thanks you for the answer

Joao Over a year ago

Do you have any example of storing a PDF into a Blob using a remote URL as the source PDF? Not locally neither using select files in HTML.

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