29 – JS Lint (ESLint)
The test runs ESLint against the website's JavaScript, looking for errors and risky patterns.
What is tested?
Among the checks are:
- that
===and!==are used instead of==and!= - that undeclared variables aren't used
- that loop conditions actually change inside the loop
- that unused variables aren't left behind
- that unnecessary escape characters aren't used
So it isn't code style being audited, but patterns that tend to be bugs.
How it affects the score
Each rule violation counts at its severity.
Running the test
python default.py -u https://example.com -t 29 -r
Worth knowing
The test audits the code delivered to the visitor. If it's bundled and minified, the review is harder to map back to your source. Run ESLint in your own build pipeline too, where you have the source.