Skip to main content
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. 
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. 
//# 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.