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Sourcemaps

Sourcemaps are a way to convert backtraces from minified or transpiled JavaScript files to their original representation in your source code. A sourcemap contains data about your front-end source code, which we can use to derive the function name, line and column number, and surrounding source code from the position referenced in the backtrace.

Requirements

Enhancing backtraces with sourcemaps requires each sample to be tagged with a revision of your application. This is used to determine when to fetch new sourcemaps after a deploy has changed your (front-end) code. You can specify the revision in the options given when creating a new AppSignal instance.

JavaScript
const appsignal = new Appsignal({
  key: "<your frontend API key>",
  revision: "<your current revision>",
});

Public sourcemaps

With public sourcemaps, the sourcemap is hosted next to the JavaScript file. At the bottom of the minified JavaScript there needs to be a special comment to indicate that a sourcemap is available for the code.

JavaScript
//# sourceMappingURL=file.js.map

The URL in this comment can be a full URL to the sourcemap, or a relative path from the JavaScript file to the sourcemap.

For example, if the minified JS is hosted on: https://your.app/assets/application.min.js and the sourcemap comment looks like //# sourceMappingURL=application.min.js.map, we will attempt to retrieve the source map from the following URL: https://your.app/assets/application.min.js.map.

We attempt to cache public sourcemaps, but we may nonetheless request the minified version and the sourcemap file more than once.

Private sourcemaps

We usually recommend using public sourcemaps whenever possible, as builds that produce lots of sourcemaps can take a long time to upload via our private sourcemap endpoint.

However, if that is not possible, you can also upload your sourcemaps to our sourcemaps API endpoint.

Retention

Sourcemaps are grouped into a "release" by the revision string and we will keep the last "release" until a new revision is uploaded. Older "releases" will be kept for up to sixty days.