Sourcemaps

When you want to improve performance, you may choose to minimize bundle size by choosing to minify the bundle size using --minify. This can be problematic when using stacktraces for debugging because the stacktrace will include the minified lines of code which do not line up with your source code at all.

One way of retaining the value of stacktraces is by adding sourcemaps. You can add sourcemaps using esbuild by adding the sourcemap=linked flag or adding the config in your build script:

sourcemap: 'linked',

You will also need to enable source maps in your NODE_OPTIONS environmental variable for your application.

NODE_OPTIONS: '--enable-source-maps

This will add a new .map file which can be quite large. This is usually not a problem for performance because it’s only loaded when an error occurs. See this article for some benchmarks.

One method dramatically reducing the bundle size of the sourcemaps is by excluding building sourcemaps for node_modules as suggested by: https://github.com/evanw/esbuild/issues/1685

This was broken in esbuild@0.25.2 with a workaround noted in: https://github.com/evanw/esbuild/issues/4130

So, the end result is that you can add source maps with minimal addition to the bundle size.