This example demonstrates how webpack tracks the usage of ES6 imports and exports. Only used exports are emitted to the resulting bundle. The minimizing step then removes the declarations because they are unused.
Excluding unused exports from bundles is known as "tree-shaking".
In this example, only add and multiply in ./math.js are used by the app. list is unused and is not included in the minimized bundle (Look for Array.from in the minimized bundle).
In addition to that, library.js simulates an entry point to a big library. library.js re-exports multiple identifiers from submodules. Often big parts of that are unused, like abc.js. Note how the usage information flows from example.js through library.js into abc.js and all declarations in abc.js are not included in the minimized bundle (Look for console.log("a") in the minimized bundle).
_{{example.js}}__{{math.js}}__{{library.js}}__{{dist/output.js}}__{{production:dist/output.js}}__{{stdout}}_
_{{production:stdout}}_