lazy-load undici

Author: targos

lib/internal/bootstrap/pre_execution.js

@@ -2,6 +2,7 @@
 
 const {
   NumberParseInt,
+  ObjectDefineProperties,
   ObjectDefineProperty,
   ObjectGetOwnPropertyDescriptor,
   SafeMap,
@@ -156,18 +157,41 @@ function setupFetch() {
     return;
   }
 
-  const undici = require('internal/deps/undici/undici');
+  let undici;
+  function lazyUndici() {
+    if (undici) {
+      return undici;
+    }
+
+    emitExperimentalWarning('The Fetch API');
+    undici = require('internal/deps/undici/undici');
+  }
 
   async function fetch(input, init = undefined) {
-    emitExperimentalWarning('Fetch');
-    return undici.fetch(input, init);
+    return lazyUndici().fetch(input, init);
   }
 
   defineOperation(globalThis, 'fetch', fetch);
-  exposeInterface(globalThis, 'FormData', undici.FormData);
-  exposeInterface(globalThis, 'Headers', undici.Headers);
-  exposeInterface(globalThis, 'Request', undici.Request);
-  exposeInterface(globalThis, 'Response', undici.Response);
+
+  function lazyInterface(name) {
+    return {
+      configurable: true,
+      enumerable: false,
+      get() {
+        return lazyUndici()[name];
+      },
+      set(value) {
+        exposeInterface(globalThis, name, value);
+      }
+    };
+  }
+
+  ObjectDefineProperties(globalThis, {
+    FormData: lazyInterface('FormData'), 
+    Headers: lazyInterface('Headers'),
+    Request: lazyInterface('Request'),
+    Response: lazyInterface('Response'),
+  });
 }
 
 // TODO(aduh95): move this to internal/bootstrap/browser when the CLI flag is

test/parallel/test-fetch.mjs

@@ -12,7 +12,7 @@ assert.strictEqual(typeof globalThis.Response, 'function');
 
 common.expectWarning(
   'ExperimentalWarning',
-  'Fetch is an experimental feature. This feature could change at any time'
+  'The Fetch API is an experimental feature. This feature could change at any time'
 );
 
 const server = http.createServer((req, res) => {