Alfa DOM

Implementation of the DOM and CSSOM specifications.

Test specificities

Because this is the package that defines Alfa's custom JSX transformation, the tests that use JSX syntax need to do some magic.

From other packages, setting jsxImportSource: "@siteimprove/alfa-dom" in the compilerOptions of the tsconfig.json file is enough to make the tests work.

However, this points to the compiled version of the JSX transformation (in the dist directory). This means that the resulting Element, … will be from the classes defined there. Which, in turns, means that if we point the test files to the uncomplied src directory, Vitest will make its own compilation resulting in different Element, … classes and breaking every instanceof, … checks (used, notably, in the isElement, … guards).

It seems that it is not possible to point the jsxImportSource to the src directory, which makes sense as Vitest needs a compiled version of it to run during its own compilation process.

Hence, the only way to use the same class for both the tests and the JSX transformation is to also have the tests import from dist, instead of doing it from src as usual; which also means importing from the .js compiled files instead of the .ts source files.