Add note specifying Source Map directive is mandatory

[ndmanvar]

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[kamilogorek]

It's already mentioned here https://docs.sentry.io/clients/javascript/sourcemaps/#hosting-source-map-files :)

[MaxBittker]

When Sentry encounters such a directive, it will resolve the source map URL relative the source file in which it is found, and attempt an HTTP request to fetch it.

^to me, this is the misleading sentence

[benvinegar]

+Note: You must have the source map directive (//# sourceMappingURL=...app.js.map) present on the last line of the minified file in order for un-minfication to occur.

The SourceMap HTTP header can also be present.

Hmm, I guess that header isn't mentioned anywhere in the docs.

[ndmanvar]

@benvinegar
Does this mean you can set the SourceMap HTTP header when uploading the minified js file, in place of having sourceMappingURL=.... at the end of the minified file? Is that correct? (Just want to make sure I'm on the same page before I start writing documentation)

[benvinegar]

Does this mean you can set the SourceMap HTTP header when uploading the minified js file, in place of having sourceMappingURL=.... at the end of the minified file? Is that correct? (Just want to make sure I'm on the same page before I start writing documentation)

I think so but I've never verified personally.

Don't forget you can also have the minified files hosted publicly return the SourceMap header, but have the source maps privately hosted on Sentry (or vice versa, though there's hardly a good reason to do that).

[dcramer]

SourceMap can also be set when you upload the artifact, effectively letting you point to an arbitrary sourcemap bundle without ever declaring anything in your minified files. That's probably the main use case for the header.

(you pass it via headers on the artifact endpoint)

[ndmanvar]

Will add documentation about the headers piece as well (i.e. don't merge this PR yet, will add some more docs clarifying on how source map linking works / what is required for proper expanding sources.