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Sourcemaps beta

Warning: Beta implementation.

This is a Beta implementation, which means:

  • We do our best to process every front-end backtrace and enrich them with sourcemap data.
  • Specific scenario's might fail, but we'll try and fix those.

Sourcemaps are a way to convert (minified) JavaScript backtraces such as https://your.host/application-minified.js:53:9895 to something a bit more helpful. A sourcemap contains data about your front-end source code and given the minified file, line number and column number, we can ask a sourcemap for the original function, line/column number and even surrounding source code.

Table of Contents


Enhancing backtraces with sourcemaps has one requirement:

  • Each sample needs to 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 (minified) 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 either be a full URL or a relative path to the sourcemap. If the URL is relative, we use the file path of the minified source to determine a full URL.

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

Our system has limited caching of public sourcemaps, this means that we can request the minified version and the sourcemap file multiple times after a deploy.

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