chore: lint .js and .mjs files (in addition to the existing .ts file linting)

[trentm]

In #2567 support
was added to eslint.config.js for linting .js and .mjs files -- before it
only supported .ts files.
Originally this was added to support linting examples/... which includes many
.js files.

This change enables linting of .js and .mjs files in the rest of the repo.

Refs: #2891

[trentm]

^^ the first commit is just the package.json changes. Subsequent commits will include lint:fix changes (and if necessary manual changes to for npm run lint to pass).

[trentm]

After running lint:fix (where 99% of changes were style-only tweaks to .eslintrc.js files), the only lint failures are in instr-aws-lambda:

      /Users/trentm/tm/opentelemetry-js-contrib2/packages/instrumentation-aws-lambda/test/lambda-test/async.js
        18:35  error  'event' is defined but never used    no-unused-vars
        18:42  error  'context' is defined but never used  no-unused-vars
        22:33  error  'event' is defined but never used    no-unused-vars
        22:40  error  'context' is defined but never used  no-unused-vars
        26:39  error  'event' is defined but never used    no-unused-vars
        26:46  error  'context' is defined but never used  no-unused-vars
        30:35  error  'event' is defined but never used    no-unused-vars
        30:42  error  'context' is defined but never used  no-unused-vars
        34:50  error  'event' is defined but never used    no-unused-vars
        34:57  error  'context' is defined but never used  no-unused-vars

      /Users/trentm/tm/opentelemetry-js-contrib2/packages/instrumentation-aws-lambda/test/lambda-test/sync.js
        22:27  error  'event' is defined but never used     no-unused-vars
        22:34  error  'context' is defined but never used   no-unused-vars
        22:43  error  'callback' is defined but never used  no-unused-vars
        30:33  error  'event' is defined but never used     no-unused-vars
        30:40  error  'context' is defined but never used   no-unused-vars
        30:49  error  'callback' is defined but never used  no-unused-vars

      ✖ 27 problems (16 errors, 11 warnings)

All are with the no-unused-vars rule.

Note that our eslint rules for TypeScript test files turn this rule off:

opentelemetry-js-contrib/eslint.config.js

Line 77 in 74ddb1e

"@typescript-eslint/no-unused-vars": "off",

We could do the same for .js files (Option 1), or add a more nuanced config something like this, which supports adding a leading _ to a var name to have it skip the "no-unused-vars" rule (Option 2):

        "no-unused-vars": [
            "error",
            {
                "vars": "all",
                "args": "all",
                "caughtErrors": "all",
                "argsIgnorePattern": "^_",
                "caughtErrorsIgnorePattern": "^_",
                "varsIgnorePattern": "^_"
            }
        ]

Anyone have opinions?

Update: In commit 092f156 I've done "Option 1".

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.55%. Comparing base (c51fef1) to head (df89efc).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2940   +/-   ##
=======================================
  Coverage   89.55%   89.55%           
=======================================
  Files         193      193           
  Lines        9698     9698           
  Branches     2011     2011           
=======================================
  Hits         8685     8685           
  Misses       1013     1013           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[trentm]

Reviewer note: We turn on the same rule for .ts files in test/... dirs.
See #2940 (comment) for discussion.

[maryliag]

phew.. a lot of files to look at 😅
thanks for working on this, looks great