If you’ve stumbled upon the strange-looking string fetch-url-file-3A-2F-2F-2F in developer forums, error logs, or URL encoding tables, you’re not alone. At first glance, it looks like a random sequence of characters. But once you URL-decode it, the meaning becomes clear:
So file-3A-2F-2F-2F decodes to file:/// — the classic file URI scheme used to access local files on a computer.
Thus, fetch-url-file-3A-2F-2F-2F essentially refers to using the fetch() API in JavaScript to request a resource from the local file system via the file:/// protocol. fetch-url-file-3A-2F-2F-2F
In this comprehensive guide, we’ll explore:
3A is the hexadecimal ASCII code for :
2F is the hexadecimal ASCII code for / So file-3A-2F-2F-2F decodes to file:/// — the classic
So:
file + 3A + 2F + 2F + 2F = file + : + / + / + /
That gives:
file:///
Thus the full decoded string is:
fetch-url-file:///
If your goal is to read a local file from a web page, here are correct, modern approaches: 3A is the hexadecimal ASCII code for :
The file:// protocol does not support CORS headers. Even if you try to fetch a local file from another local file, the browser blocks it with an error like:
Access to fetch at ‘file:///C:/data.json’ from origin ‘null’ has been blocked by CORS policy.
