Bail out early for (compiled) JSON files (resolves #883)

Author: webpro

packages/knip/fixtures/compilers/compiled.json

@@ -0,0 +1 @@
+{}

packages/knip/fixtures/compilers/index.ts

@@ -1,6 +1,8 @@
 import identifier from './module.mdx';
 import Component from './Component.vue';
 import { createApp } from 'vue';
+import data from './compiled.json';
 
 identifier;
 createApp(Component);
+data;

packages/knip/fixtures/compilers/knip.ts

@@ -6,6 +6,12 @@ export default {
       if (!path) throw new Error('Path not passed to compiler');
       return '';
     },
+    json: (content, fileName) => {
+      if (fileName.includes('compiled')) {
+        return `export default ${content}`;
+      }
+      return content;
+    },
     css: async (text: string) => {
       return [...text.matchAll(/(?<=@)import[^;]+/g)].join('\n');
     },

packages/knip/fixtures/compilers/tsconfig.json

@@ -1,6 +1,9 @@
 {
   "compilerOptions": {
     "target": "ES2015",
-    "jsx": "preserve"
+    "jsx": "preserve",
+    "resolveJsonModule": true,
+    "module": "nodenext",
+    "moduleResolution": "nodenext"
   }
 }

packages/knip/src/ProjectPrincipal.ts

@@ -11,8 +11,10 @@ import type { SourceFileManager } from './typescript/SourceFileManager.js';
 import { createHosts } from './typescript/create-hosts.js';
 import { _getImportsAndExports } from './typescript/get-imports-and-exports.js';
 import type { ResolveModuleNames } from './typescript/resolve-module-names.js';
+import { isJSON } from './typescript/visitors/helpers.js';
 import { timerify } from './util/Performance.js';
 import { compact } from './util/array.js';
+import { createExport, createFileNode } from './util/dependency-graph.js';
 import { getPackageNameFromModuleSpecifier, isStartsLikePackageName, sanitizeSpecifier } from './util/modules.js';
 import { dirname, extname, isInNodeModules, join } from './util/path.js';
 import type { ToSourceFilePath } from './util/to-source-path.js';
@@ -244,6 +246,14 @@ export class ProjectPrincipal {
 
     const skipExports = this.skipExportsAnalysis.has(filePath);
 
+    if (isJSON(sourceFile)) {
+      // Exception to allow .json files to be imported + compiled conditionally
+      const fileNode = createFileNode();
+      if (/^\s*[[{]/.test(sourceFile.text)) return fileNode;
+      fileNode.exports.set('default', createExport({ identifier: 'default' }));
+      return fileNode;
+    }
+
     const resolve = (specifier: string) => this.backend.resolveModuleNames([specifier], sourceFile.fileName)[0];
 
     const { imports, ...rest } = _getImportsAndExports(sourceFile, resolve, typeChecker, { ...options, skipExports });

packages/knip/src/typescript/visitors/helpers.ts

@@ -9,6 +9,8 @@ export const isJS = (sourceFile: BoundSourceFile) =>
 
 export const isModule = (sourceFile: BoundSourceFile) => ts.isExternalModule(sourceFile);
 
+export const isJSON = (sourceFile: BoundSourceFile) => sourceFile.scriptKind === ts.ScriptKind.JSON;
+
 export function getImportsFromPragmas(sourceFile: BoundSourceFile) {
   const importNodes: ImportNode[] = [];
 

packages/knip/src/util/dependency-graph.ts

@@ -1,11 +1,13 @@
 import type {
   DependencyGraph,
+  Export,
   FileNode,
   IdToFileMap,
   IdToNsToFileMap,
   ImportDetails,
   ImportMap,
 } from '../types/dependency-graph.js';
+import { SymbolType } from '../types/issues.js';
 
 export const getOrCreateFileNode = (graph: DependencyGraph, filePath: string) =>
   graph.get(filePath) ?? createFileNode();
@@ -34,7 +36,7 @@ export const updateImportMap = (file: FileNode, importMap: ImportMap, graph: Dep
   }
 };
 
-const createFileNode = (): FileNode => ({
+export const createFileNode = (): FileNode => ({
   imports: {
     internal: new Map(),
     external: new Set(),
@@ -46,6 +48,19 @@ const createFileNode = (): FileNode => ({
   traceRefs: new Set(),
 });
 
+export const createExport = ({ identifier }: { identifier: string }): Export => ({
+  identifier,
+  pos: 0,
+  line: 1,
+  col: 1,
+  type: SymbolType.UNKNOWN,
+  members: [],
+  jsDocTags: new Set(),
+  refs: [0, false],
+  fixes: [],
+  isReExport: false,
+});
+
 export const createImports = (): ImportDetails => ({
   refs: new Set(),
   imported: new Map(),

packages/knip/test/compilers.test.ts

@@ -15,11 +15,13 @@ test('Support compiler functions in config', async () => {
 
   assert(issues.files.has(join(cwd, 'unused.css')));
   assert(issues.files.has(join(cwd, 'unused.md')));
+  assert(issues.files.has(join(cwd, 'package.json')));
+  assert(issues.files.has(join(cwd, 'tsconfig.json')));
 
   assert.deepEqual(counters, {
     ...baseCounters,
-    files: 2,
-    processed: 11,
-    total: 11,
+    files: 4,
+    processed: 14,
+    total: 14,
   });
 });