Read a file as binary data in JavaScript on the client side

Question

As the question states, I'd like some way to read files on the client side using JavaScript (is there any other possible alternative?).

These files(images mostly) are part of the webpage, and so I do not need access to the filesystem.

So basically my question should reduce to, is it possible to open a file in binary mode in JavaScript and read it byte by byte?

There seems to be some confusion as to what I'm trying to achieve. The question How do I load binary image data using Javascript and XMLHttpRequest? deals with the case when the user is actually able make his own requests to the server and set his own mime-types etc.

I wish to create a js function/script that reads the already loaded files on the web-page as binary, for the purposes of meta-data extraction.

possible duplicate of How do I load binary image data using Javascript and XMLHttpRequest? — C3roe
– C3roe, Commented Apr 9, 2013 at 9:05
see perhaps stackoverflow.com/questions/80980/… --- Although the accepted answer was that image processing needed to be done on the server, there may be some interesting libraries mentioned amongst the other answers — Paul
– Paul, Commented Apr 9, 2013 at 9:06
Can we please remove the duplicate flag if the edit justifies why it is different from the mentioned question? — ffledgling
– ffledgling, Commented Apr 24, 2013 at 17:58

David · Accepted Answer · 2023-02-14 18:47:38Z

0

This might not have existed back when you asked but now with the FileReader API you can load a local file client side only.

answered Feb 14, 2023 at 18:47

David

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