Should fetching local files always results in a TypeError?

Hi there,

When loading local files I bump into TypeError: Network request failed right away due to the response.status of local requests being 0, thus getting rejected by fetch’s initial status handling.

In the README I see the portion on Handling HTTP error statuses, but that would only work if fetch’s initial xhr.onload didn’t reject with a TypeError first.

Would it be reasonable to change fetch’s initial status handling to something like this so that local fetches could make it through?

if ((status !== 0 && status < 100) || status > 599) {
    reject(new TypeError('Network request failed'))
    return
}

For context. I’m working on a project in which the same codebase runs:

1. In Browser, loading local files via a local dev server (no problems here)
2. Ejecta in iOS, loading purely local files (which is where I’m getting my status === 0)

Thanks!

[LMLB]

Firefox does allow XMLHttpRequest and Fetch on local files if the page is a local file and and the requested file is in the same directory (or any number of subdirectories) relative to the page.

[mislav]

Even though Safari allows XMLHttpRequest using the file: protocol (and we do nothing in the polyfill to prevent it), Chrome and Firefox access restrictions disallow it. Still, the error thrown as a result of that XHR restriction doesn’t match the TypeError thrown when native fetch is used.

But, we might not want to care about this mismatch. “Fixing” the type of the error thrown would be too much work since detecting file: protocol URLs may be tricky.