fix: remove javascript grammar

[tean-lai]

Resolves LANG-592.

Semgrep uses the typescript tree-sitter parser for javascript, so the semgrep-javascript grammar is outdated. This PR removes it.

In the future:

• semgrep-javascript is deprecated
• javascript is considered a sublang of typescript

Checklist

• Any new parsing code was already published, integrated, and merged into Semgrep. DO NOT MERGE THIS PR BEFORE THE SEMGREP INTEGRATION WORK WAS COMPLETED.
• Change has no security implications (otherwise, ping the security team)

[nmote]

Probably also worth archiving https://github.com/semgrep/semgrep-javascript

[nmote]

Probably less confusing to just remove this symlink altogether

[tean-lai]

The plan was to archive semgrep-javascript, but I seem to have insufficient perms at the moment.

Keeping the symlink seems to be more consistent with other stuff. Thinking particularly of tsx, which we treat as a sublang of typescript already, but that similarly symlinks to semgrep-typescript/tsx. It also seems like the test-lang script depends on the existence of this symlink.

[malaverdiere]

Review: JavaScript-grammar removal

Checked whether automated tests still pass, whether the TypeScript grammar is affected, and swept for leftover JavaScript references. Verified all of this by actually running the scripts locally (initialized the tree-sitter-javascript/tree-sitter-typescript submodules, ran prep, ran the vendored tree-sitter 0.22.6 binary directly), not just by reading the diff.

✅ Already fixed by 8693d43 ("fix corpus symlink for javascript")

lang/semgrep-grammars/src/semgrep-typescript/prep originally pointed javascript/corpus/inherited at ../../../tree-sitter-javascript/javascript/corpus, which doesn't exist (tree-sitter-javascript is a flat repo — corpus lives at test/corpus). That's been corrected to ../../../tree-sitter-javascript/test/corpus. Confirmed the symlink resolves now. (For what it's worth, I also confirmed this specific corpus-test path is inert either way today — tree-sitter test only reads test/corpus, not bare corpus, and these sublang dirs use corpus/ directly — so this was latent either way, not an active regression. Still, good to have it correct.)

🔴 Still open — will break CI

.circleci/config.yml:159 still lists - javascript in the test-language matrix. That job runs ./test-lang javascript, whose very first line is cd semgrep-grammars/src/semgrep-javascript — a directory this PR deletes (c9e95e5 remove semgrep-javascript). I reproduced the failure locally:

$ cd lang && cd semgrep-grammars/src/semgrep-javascript
cd: semgrep-grammars/src/semgrep-javascript: No such file or directory

There's no allow_failure/continue-on-error on this job, so it'll hard-fail on every push. lang/Makefile's own coupling comment says any SUPPORTED_TS_LANGUAGES change must be mirrored here — javascript was correctly dropped from the Makefile lists but the CircleCI matrix entry wasn't. Since javascript is now a sublang of typescript (like tsx, which also isn't listed separately here), it should just be removed from this matrix.

🟡 Minor — stale JavaScript references left behind

• doc/fix-semgrep-grammar-skill.md:9 and :24 still use javascript as the test-lang example (e.g. javascript, test-lang javascript pass), while the canonical .agents/skills/fix-semgrep-grammar/SKILL.md had its matching examples swapped to typescript in this PR (09c990f). Worth syncing so the two docs don't drift.
• .agents/skills/fix-semgrep-grammar/SKILL.md:215 still says "semgrep-javascript's _jsx_child" as a worked example — that directory is gone; the rule now lives at lang/semgrep-grammars/src/semgrep-typescript/javascript/grammar.js. Worth rewording so it doesn't point at a directory that no longer exists.

TypeScript grammar

Unaffected. The prep script's typescript/tsx blocks are untouched, and none of the javascript-related additions can abort the script early (no early exit before the typescript/tsx blocks run).