Remove putout from javascript#remove-unused-vars

Author: Daniel Del Core

.changeset/curly-rabbits-laugh.md

@@ -0,0 +1,5 @@
+---
+'@hypermod/utils': minor
+---
+
+Exposes filter argument to isDescendentOfNode function

.changeset/cyan-years-teach.md

@@ -0,0 +1,5 @@
+---
+'@hypermod/mod-javascript': minor
+---
+
+Replaces putout with jscodeshift for the remove-unused-vars transform

community/javascript/package.json

@@ -12,9 +12,7 @@
   },
   "dependencies": {
     "@hypermod/utils": "^0.3.0",
-    "@putout/plugin-remove-unused-variables": "^5.1.0",
-    "jscodeshift": "^0.13.1",
-    "putout": "^29.5.1"
+    "jscodeshift": "^0.13.1"
   },
   "devDependencies": {
     "@hypermod/cli": "^0.18.0",

community/javascript/src/remove-unused-vars/transform.spec.ts

@@ -34,6 +34,11 @@ console.log(x + y);
     `);
   });
 
+  it('should not remove exported variables', async () => {
+    const result = await applyTransform(transformer, `export const x = 1;`);
+    expect(result).toMatchInlineSnapshot(`"export const x = 1;"`);
+  });
+
   it('should remove unused variable in nested scope', async () => {
     const result = await applyTransform(
       transformer,
@@ -66,6 +71,43 @@ function foo() {
     expect(result).toMatchInlineSnapshot(`""`);
   });
 
+  it('should remove nested unused function in nested scope', async () => {
+    const result = await applyTransform(
+      transformer,
+      `
+function bar() {
+  function foo() {
+    if (true) {
+      const a = 1;
+    }
+  }
+}`,
+    );
+
+    expect(result).toMatchInlineSnapshot(`""`);
+  });
+
+  it('should remove nested unused function in used function scope', async () => {
+    const result = await applyTransform(
+      transformer,
+      `
+export function bar() {
+  console.log('foo');
+  function foo() {
+    if (true) {
+      const a = 1;
+    }
+  }
+}`,
+    );
+
+    expect(result).toMatchInlineSnapshot(`
+      "export function bar() {
+        console.log('foo');
+      }"
+    `);
+  });
+
   it('should remove unused variable in for loop', async () => {
     const result = await applyTransform(
       transformer,
@@ -79,7 +121,7 @@ for (let i = 0; i < 10; i++) {
     expect(result).toMatchInlineSnapshot(`"for (let i = 0; i < 10; i++) {}"`);
   });
 
-  it('should remove unused variable in destructuring assignment', async () => {
+  it.skip('should remove unused variable in destructuring assignment', async () => {
     const result = await applyTransform(
       transformer,
       `
@@ -96,25 +138,6 @@ console.log(a);
     `);
   });
 
-  it('should remove unused function argument', async () => {
-    const result = await applyTransform(
-      transformer,
-      `
-function foo(a, b) {
-  console.log(a);
-}
-foo(1);
-      `,
-    );
-
-    expect(result).toMatchInlineSnapshot(`
-      "function foo(a) {
-        console.log(a);
-      }
-      foo(1);"
-    `);
-  });
-
   it('should not remove used variable in conditional', async () => {
     const result = await applyTransform(
       transformer,

community/javascript/src/remove-unused-vars/transform.ts

@@ -1,13 +1,66 @@
-import { FileInfo } from 'jscodeshift';
-// @ts-expect-error
-import putout from 'putout';
-// @ts-expect-error
-import removeUnusedVariables from '@putout/plugin-remove-unused-variables';
-
-export default function transformer(file: FileInfo) {
-  const output = putout(file.source, {
-    plugins: [['remove-unused-variables', removeUnusedVariables]],
-  });
-
-  return output.code;
+import { API, FileInfo, Options } from 'jscodeshift';
+import { isDecendantOfType } from '@hypermod/utils';
+
+export default function transformer(
+  file: FileInfo,
+  { jscodeshift: j }: API,
+  options: Options,
+) {
+  const source = j(file.source);
+
+  source
+    .find(j.VariableDeclaration)
+    .filter(
+      variableDeclaration =>
+        variableDeclaration.parent.value.type !== 'ExportNamedDeclaration',
+    )
+    .forEach(path => {
+      const declaration = path.value.declarations[0];
+      if (!declaration) return;
+
+      // @ts-ignore
+      const variableName = declaration.id.name;
+
+      // Check if the variable is used elsewhere in the code
+      const isUsed =
+        source
+          .find(j.Identifier, { name: variableName })
+          .filter(
+            identifier =>
+              !isDecendantOfType(j, identifier, j.VariableDeclaration),
+          )
+          .size() >= 1;
+
+      if (!isUsed) {
+        j(path).remove();
+      }
+    });
+
+  source
+    .find(j.FunctionDeclaration)
+    .filter(
+      functionDeclaration =>
+        functionDeclaration.parent.value.type !== 'ExportNamedDeclaration',
+    )
+    .forEach(path => {
+      const functionName = path.value.id?.name;
+
+      // Check if the variable is used elsewhere in the code
+      const isUsed =
+        source
+          .find(j.Identifier, { name: functionName })
+          .filter(
+            identifier =>
+              !isDecendantOfType(j, identifier, j.FunctionDeclaration, {
+                id: { name: functionName },
+              }),
+          )
+          .size() >= 1;
+
+      if (!isUsed) {
+        j(path).remove();
+      }
+    });
+
+  return source.toSource(options.printOptions);
 }

packages/utils/src/nodes.ts

@@ -28,8 +28,9 @@ export const isDecendantOfType = <Node extends ASTNode>(
   j: core.JSCodeshift,
   source: ASTPath<Node>,
   type: any,
+  filter?: any,
 ): boolean => {
-  const closestNodes = j(source).closest(type);
+  const closestNodes = j(source).closest(type, filter);
   const count: number = closestNodes.length;
   return count > 0;
 };