fix(esm): adjust to new Node 16 loader API

introduced in 16.12.0
AviVahl · Oct 20, 2021 · cb78177 · cb78177
1 parent 660e9b4
commit cb78177
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Showing 3 changed files with 46 additions and 48 deletions.
diff --git a/packages/esm/src/create-loader.ts b/packages/esm/src/create-loader.ts
@@ -1,25 +1,24 @@
+import { readFileSync } from 'fs';
 import { pathToFileURL, fileURLToPath } from 'url';
 import ts from 'typescript';
 
 const isTypescriptFile = (url: string) => url.endsWith('.ts') || url.endsWith('.tsx');
 
-/** @url https://nodejs.org/docs/latest-v16.x/api/esm.html#esm_resolve_specifier_context_defaultresolve */
+export type ModuleFormat = 'builtin' | 'commonjs' | 'json' | 'module' | 'wasm';
+
+/** @url https://nodejs.org/docs/latest-v16.x/api/esm.html#resolvespecifier-context-defaultresolve */
 export type ResolveHook = (
   specifier: string,
-  context: { parentURL: string; conditions: string[] },
+  context: { parentURL?: string; conditions: string[] },
   defaultResolve: ResolveHook
-) => { url: string };
-
-/** @url https://nodejs.org/docs/latest-v16.x/api/esm.html#esm_getformat_url_context_defaultgetformat */
-export type FormatHook = (url: string, context: {}, defaultGetFormat: FormatHook) => { format: ModuleFormat };
-export type ModuleFormat = 'builtin' | 'commonjs' | 'json' | 'module' | 'wasm';
+) => { url: string; format?: ModuleFormat };
 
-/** @url https://nodejs.org/docs/latest-v16.x/api/esm.html#esm_transformsource_source_context_defaulttransformsource */
-export type TransformHook = (
-  source: string | SharedArrayBuffer | Uint8Array,
-  context: { url: string; format: ModuleFormat },
-  defaultTransformSource: TransformHook
-) => { source: string | SharedArrayBuffer | Uint8Array };
+/** @url https://nodejs.org/docs/latest-v16.x/api/esm.html#loadurl-context-defaultload */
+export type LoadHook = (
+  url: string,
+  context: { format?: ModuleFormat },
+  defaultTransformSource: LoadHook
+) => { source: string | SharedArrayBuffer | Uint8Array; format: ModuleFormat };
 
 export interface CreateLoaderOptions {
   compilerOptions: ts.CompilerOptions;
@@ -53,25 +52,24 @@ export function createLoader({ compilerOptions, cwd }: CreateLoaderOptions) {
     return defaultResolve(specifier, context, defaultResolve);
   };
 
-  const getFormat: FormatHook = (url, context, defaultGetFormat) => {
-    return isTypescriptFile(url) ? { format: 'module' } : defaultGetFormat(url, context, defaultGetFormat);
+  const load: LoadHook = (url, context, defaultTransformSource) => {
+    if (isTypescriptFile(url)) {
+      const filePath = fileURLToPath(url);
+      const source = readFileSync(filePath, 'utf8');
+      return {
+        source: ts.transpileModule(source, {
+          fileName: filePath,
+          compilerOptions,
+        }).outputText,
+        format: 'module',
+      };
+    } else {
+      return defaultTransformSource(url, context, defaultTransformSource);
+    }
   };
 
-  const transformSource: TransformHook = (source, context, defaultTransformSource) => {
-    const { url } = context;
-
-    return isTypescriptFile(url)
-      ? {
-          source: ts.transpileModule(source.toString(), {
-            fileName: fileURLToPath(url),
-            compilerOptions,
-          }).outputText,
-        }
-      : defaultTransformSource(source, context, defaultTransformSource);
-  };
   return {
     resolve,
-    getFormat,
-    transformSource,
+    load,
   };
 }
diff --git a/packages/esm/src/default-loader.ts b/packages/esm/src/default-loader.ts
@@ -14,6 +14,6 @@ const cwd = process.cwd();
 const tsconfigPath = ts.findConfigFile(cwd, ts.sys.fileExists);
 const compilerOptions = tsconfigPath !== undefined ? loadTsconfig(tsconfigPath) : defaultCompilerOptions;
 
-const { resolve, getFormat, transformSource } = createLoader({ compilerOptions, cwd });
+const { resolve, load } = createLoader({ compilerOptions, cwd });
 
-export { resolve, getFormat, transformSource };
+export { resolve, load };
diff --git a/packages/esm/test/esm-loader.unit.ts b/packages/esm/test/esm-loader.unit.ts
@@ -14,21 +14,21 @@ export function runCommand(command: string): { output: string; exitCode: number
   return { output: output.join('\n'), exitCode: exitCode || 0 };
 }
 
-describe('using node --experimental-loader @ts-tools/esm <file>', function () {
-  this.timeout(5000);
+if (nodeMajorVersion >= 16) {
+  describe('using node --experimental-loader @ts-tools/esm <file>', function () {
+    this.timeout(5000);
 
-  describe('when tsconfig.json is found', () => {
-    it('allows using imports (with default interop)', () => {
-      const filePath = join(fixturesRoot, 'imports.ts');
+    describe('when tsconfig.json is found', () => {
+      it('allows using imports (with default interop)', () => {
+        const filePath = join(fixturesRoot, 'imports.ts');
 
-      const { output, exitCode } = runCommand(`node --experimental-loader @ts-tools/esm ${filePath}`);
+        const { output, exitCode } = runCommand(`node --experimental-loader @ts-tools/esm ${filePath}`);
 
-      expect(exitCode).to.equal(0);
-      expect(output).to.include(`Current platform is: ${platform()}`);
-      expect(output).to.include(`Path separator is: ${sep}`);
-    });
+        expect(exitCode).to.equal(0);
+        expect(output).to.include(`Current platform is: ${platform()}`);
+        expect(output).to.include(`Path separator is: ${sep}`);
+      });
 
-    if (nodeMajorVersion >= 14) {
       it('maps stack traces using source maps when specifying --enable-source-maps', () => {
         const filePath = join(fixturesRoot, 'throwing.ts');
 
@@ -39,14 +39,14 @@ describe('using node --experimental-loader @ts-tools/esm <file>', function () {
         expect(exitCode).to.not.equal(0);
         expect(output).to.include(`runMe (${filePath}:10:11)`);
       });
-    }
 
-    it('does not throw on empty files', () => {
-      const filePath = join(fixturesRoot, 'empty.ts');
+      it('does not throw on empty files', () => {
+        const filePath = join(fixturesRoot, 'empty.ts');
 
-      const { exitCode, output } = runCommand(`node --experimental-loader @ts-tools/esm ${filePath}`);
+        const { exitCode, output } = runCommand(`node --experimental-loader @ts-tools/esm ${filePath}`);
 
-      expect(exitCode, output).to.equal(0);
+        expect(exitCode, output).to.equal(0);
+      });
     });
   });
-});
+}