chore: add oxlint and remove unnecessary optional chaining

.github/workflows/ci.yml

@@ -43,3 +43,13 @@ jobs:
           node-version: latest
       - run: npm ci
       - run: npm run format:check
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: actions/setup-node@v7
+        with:
+          node-version: latest
+      - run: npm ci
+      - run: npm run lint

eslint.config.mjs

@@ -0,0 +1,43 @@
+'use strict';
+
+// The http and http2 diagnostics channels publish headers after they are
+// parsed, so a `.headers` object is always present by the time any handler
+// runs. Optional chaining on it is dead code and hides real mistakes.
+const banOptionalChainingOnHeaders = () => ({
+  selector: "MemberExpression[optional=true][object.property.name='headers']",
+  message:
+    'Optional chaining on .headers is unnecessary: the diagnostics ' +
+    'channels publish headers after parsing, so they are always an object.',
+});
+
+export default [
+  {
+    files: ['lib/**/*.js', 'test/**/*.js', 'benchmark/**/*.js', 'index.js'],
+    languageOptions: {
+      ecmaVersion: 'latest',
+      sourceType: 'commonjs',
+      globals: {
+        console: 'readonly',
+        process: 'readonly',
+        Buffer: 'readonly',
+        URL: 'readonly',
+        setTimeout: 'readonly',
+        clearTimeout: 'readonly',
+        setInterval: 'readonly',
+        clearInterval: 'readonly',
+        setImmediate: 'readonly',
+        fetch: 'readonly',
+      },
+    },
+    rules: {
+      'no-unused-vars': [
+        'error',
+        { argsIgnorePattern: '^_', varsIgnorePattern: '^_' },
+      ],
+      'no-restricted-syntax': ['error', banOptionalChainingOnHeaders()],
+    },
+  },
+  {
+    ignores: ['node_modules/', 'test/fixtures/'],
+  },
+];

lib/id.js

@@ -11,7 +11,7 @@ const kBufferSize = 4096;
 const randomBuffer = new Uint8Array(kBufferSize);
 let randomOffset = kBufferSize; // Start at end to trigger first fill
 
-const hexTable = new Array(256);
+const hexTable = Array.from({ length: 256 });
 for (let i = 0; i < 256; i++) hexTable[i] = i.toString(16).padStart(2, '0');
 
 function ensureRandomBytes(needed) {

lib/instrumentations.js

@@ -229,16 +229,16 @@ function onHttp2ServerStreamStart({ stream, headers }) {
   // Exports travel over HTTP/1.1, so an export request can never arrive as
   // an HTTP/2 stream and the self-trace suppression the http handlers need
   // does not apply here.
-  const traceparent = headers?.traceparent;
+  const traceparent = headers.traceparent;
   const parent =
     traceparent != null ? Span.fromTraceparent(traceparent) : undefined;
   // Per the W3C Trace Context spec, tracestate is only meaningful
   // alongside a valid traceparent. It is discarded when the traceparent
   // is absent or rejected, same as for HTTP/1.1 requests.
-  const tracestate = parent != null ? headers?.tracestate : undefined;
+  const tracestate = parent != null ? headers.tracestate : undefined;
 
-  const method = headers?.[':method'] || 'GET';
-  const rawUrl = headers?.[':path'] || '/';
+  const method = headers[':method'] || 'GET';
+  const rawUrl = headers[':path'] || '/';
   const qIdx = rawUrl.indexOf('?');
   const path = qIdx === -1 ? rawUrl : rawUrl.slice(0, qIdx);
 
@@ -257,11 +257,11 @@ function onHttp2ServerStreamStart({ stream, headers }) {
   // socket check for HTTP/1.1.
   span.setAttribute(
     'url.scheme',
-    headers?.[':scheme'] || (stream?.session?.encrypted ? 'https' : 'http'),
+    headers[':scheme'] || (stream?.session?.encrypted ? 'https' : 'http'),
   );
   span.setAttribute('network.protocol.version', '2.0');
 
-  const authority = headers?.[':authority'];
+  const authority = headers[':authority'];
   if (authority) span.setAttribute('server.address', authority);
 
   // The span is stashed on the stream so the finish and close handlers do
@@ -281,7 +281,7 @@ function onHttp2ServerStreamStart({ stream, headers }) {
 // key/value pairs, and the channel publishes whichever form was used.
 function getH2Header(headers, name) {
   if (Array.isArray(headers)) return headers[headers.indexOf(name) + 1];
-  return headers?.[name];
+  return headers[name];
 }
 
 function onHttp2ServerStreamFinish({ stream, headers }) {