How to convert/decode base64 from XHR request response string

user_7163711 0
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I keep facing a problem converting XHR request response properly. I've read couple of solutions on Stackoverflow and on some other platforms but couldn't success to convert string to dataURL.

I've tried to convert string to through atob() and btoa() methods mention on MDN and this Stackoverflow post. + I've keep dive much to find a solution within lost of different methods but non of them took me aim.

How can I convert this response below to a dataURL properly to be able set the URL as image src?

XHR Request Response:

    "�PNG


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UPDATE:

I've succeed to render image through this post @ https://stackoverflow.com/a/8022521/7163711

data-uri response base64 image javascript
1 Answers

Your XHR data is a png file, as expected. In order to show you how to embed it properly, I've taken the liberty of generating a "better" PNG - a 10x10 yellow square. it is base64-encoded in b64data on the first line of the snippet. The second line sets yourData as what you would have gotten from an XHR.

var b64data = "iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAYAAACNMs+9AAAAFklEQVR42mP8/5/hDAMRgHFUIX0VAgBfZRvvtreybgAAAABJRU5ErkJggg==";

// Assuming your data is a raw PNG
var yourData = atob(b64data);

// We convert...
var btoa_data = btoa(yourData);

var elem = document.createElement("img");
elem.src = "data:image/png;base64,"+btoa_data;
document.getElementById("app").append(elem);
console.log(atob(b64data));
<div id="app"></div>

As you can see, btoa() works in order to base64-encode data; the only thing you need to do after this is to indicate in the src part of your img tag that:

  • It is a PNG (if it isn't, or if you are not sure if it will be, you'll need to check the first few bytes of your reply)
  • It is base64-encoded
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