From 49e670c223ce81049a640b6c9a3e004b5747ccc6 Mon Sep 17 00:00:00 2001
From: Colby McHenry <me@colbymchenry.com>
Date: Tue, 7 Apr 2026 09:40:50 -0500
Subject: [PATCH] feat: Add resolveBody hook for JS/TS class field function
 extraction
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Addresses arrow function class fields like `field = () => { ... }` where the function body is nested inside field_definition nodes. Adds resolveBody method to traverse field_definition → arrow_function/function_expression → body and handles HOF wrapper patterns like `field = throttle(() => { ... })` by searching call_expression arguments. Enables proper function body extraction for class field functions in both JavaScript and TypeScript.
---
 src/extraction/languages/javascript.ts | 28 +++++++++++++++++++++++++
 src/extraction/languages/typescript.ts | 29 ++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/src/extraction/languages/javascript.ts b/src/extraction/languages/javascript.ts
index 15b255b..0a0d678 100644
--- a/src/extraction/languages/javascript.ts
+++ b/src/extraction/languages/javascript.ts
@@ -14,6 +14,34 @@ export const javascriptExtractor: LanguageExtractor = {
   variableTypes: ['lexical_declaration', 'variable_declaration'],
   nameField: 'name',
   bodyField: 'body',
+  resolveBody: (node, bodyField) => {
+    // field_definition (arrow function class fields) nest the body inside
+    // an arrow_function or function_expression child:
+    //   field_definition → arrow_function → body (statement_block)
+    // Also handles wrapper patterns like: field = throttle((e) => { ... })
+    //   field_definition → call_expression → arguments → arrow_function → body
+    if (node.type === 'field_definition') {
+      for (let i = 0; i < node.namedChildCount; i++) {
+        const child = node.namedChild(i);
+        if (!child) continue;
+        if (child.type === 'arrow_function' || child.type === 'function_expression') {
+          return getChildByField(child, bodyField);
+        }
+        if (child.type === 'call_expression') {
+          const args = getChildByField(child, 'arguments');
+          if (args) {
+            for (let j = 0; j < args.namedChildCount; j++) {
+              const arg = args.namedChild(j);
+              if (arg && (arg.type === 'arrow_function' || arg.type === 'function_expression')) {
+                return getChildByField(arg, bodyField);
+              }
+            }
+          }
+        }
+      }
+    }
+    return null;
+  },
   paramsField: 'parameters',
   getSignature: (node, source) => {
     const params = getChildByField(node, 'parameters');
diff --git a/src/extraction/languages/typescript.ts b/src/extraction/languages/typescript.ts
index 230a2a3..9c91438 100644
--- a/src/extraction/languages/typescript.ts
+++ b/src/extraction/languages/typescript.ts
@@ -15,6 +15,35 @@ export const typescriptExtractor: LanguageExtractor = {
   variableTypes: ['lexical_declaration', 'variable_declaration'],
   nameField: 'name',
   bodyField: 'body',
+  resolveBody: (node, bodyField) => {
+    // public_field_definition (arrow function class fields) nest the body inside
+    // an arrow_function or function_expression child:
+    //   public_field_definition → arrow_function → body (statement_block)
+    // Also handles wrapper patterns like: field = withBatchedUpdates((e) => { ... })
+    //   public_field_definition → call_expression → arguments → arrow_function → body
+    if (node.type === 'public_field_definition') {
+      for (let i = 0; i < node.namedChildCount; i++) {
+        const child = node.namedChild(i);
+        if (!child) continue;
+        if (child.type === 'arrow_function' || child.type === 'function_expression') {
+          return getChildByField(child, bodyField);
+        }
+        // Check inside call_expression arguments (HOF wrappers like throttle, debounce)
+        if (child.type === 'call_expression') {
+          const args = getChildByField(child, 'arguments');
+          if (args) {
+            for (let j = 0; j < args.namedChildCount; j++) {
+              const arg = args.namedChild(j);
+              if (arg && (arg.type === 'arrow_function' || arg.type === 'function_expression')) {
+                return getChildByField(arg, bodyField);
+              }
+            }
+          }
+        }
+      }
+    }
+    return null;
+  },
   paramsField: 'parameters',
   returnField: 'return_type',
   getSignature: (node, source) => {