chore: move index.js into src (#6007)

* chore: move `index.js` into `src`

This is the first part of a series of pull requests that will slowly
make it possible to initialise Puppeteer for either a Node environment
or a web one. By creating the `initialisePuppeteer` function we can
inject dependencies in for the given version of Puppeteer (e.g. inject a
different debug library for Node vs the web).

This PR moves the initialisation into `src` and calls into it from the
root `index.js`.

index.js

@@ -14,40 +14,11 @@
  * limitations under the License.
  */
 
-const { helper } = require('./lib/helper');
-const api = require('./lib/api');
-const { Page } = require('./lib/Page');
-for (const className in api) {
-  if (typeof api[className] === 'function')
-    helper.installAsyncStackHooks(api[className]);
-}
+const { initializePuppeteer } = require('./lib/index');
 
-// Expose alias for deprecated method.
-Page.prototype.emulateMedia = Page.prototype.emulateMediaType;
-
-const { Puppeteer } = require('./lib/Puppeteer');
-const packageJson = require('./package.json');
-let preferredRevision = packageJson.puppeteer.chromium_revision;
-const isPuppeteerCore = packageJson.name === 'puppeteer-core';
-// puppeteer-core ignores environment variables
-const product = isPuppeteerCore
-  ? undefined
-  : process.env.PUPPETEER_PRODUCT ||
-    process.env.npm_config_puppeteer_product ||
-    process.env.npm_package_config_puppeteer_product;
-if (!isPuppeteerCore && product === 'firefox')
-  preferredRevision = packageJson.puppeteer.firefox_revision;
-
-const puppeteer = new Puppeteer(
-  __dirname,
-  preferredRevision,
-  isPuppeteerCore,
-  product
-);
-
-// The introspection in `Helper.installAsyncStackHooks` references `Puppeteer._launcher`
-// before the Puppeteer ctor is called, such that an invalid Launcher is selected at import,
-// so we reset it.
-puppeteer._lazyLauncher = undefined;
+const puppeteer = initializePuppeteer({
+  packageJson: require('./package.json'),
+  rootDirectory: __dirname,
+});
 
 module.exports = puppeteer;

src/index.ts

@@ -0,0 +1,72 @@
+/**
+ * Copyright 2020 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// api.ts has to use module.exports as it's also consumed by DocLint which runs
+// on Node.
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const api = require('./api');
+
+import { helper } from './helper';
+import { Page } from './Page';
+import { Puppeteer } from './Puppeteer';
+
+interface InitOptions {
+  packageJson: {
+    puppeteer: {
+      chromium_revision: string;
+      firefox_revision: string;
+    };
+    name: string;
+  };
+  rootDirectory: string;
+}
+
+export const initializePuppeteer = (options: InitOptions): Puppeteer => {
+  const { packageJson, rootDirectory } = options;
+
+  for (const className in api) {
+    if (typeof api[className] === 'function')
+      helper.installAsyncStackHooks(api[className]);
+  }
+
+  // Expose alias for deprecated method.
+  // @ts-expect-error emulateMedia does not exist error
+  Page.prototype.emulateMedia = Page.prototype.emulateMediaType;
+
+  let preferredRevision = packageJson.puppeteer.chromium_revision;
+  const isPuppeteerCore = packageJson.name === 'puppeteer-core';
+  // puppeteer-core ignores environment variables
+  const product = isPuppeteerCore
+    ? undefined
+    : process.env.PUPPETEER_PRODUCT ||
+      process.env.npm_config_puppeteer_product ||
+      process.env.npm_package_config_puppeteer_product;
+  if (!isPuppeteerCore && product === 'firefox')
+    preferredRevision = packageJson.puppeteer.firefox_revision;
+
+  const puppeteer = new Puppeteer(
+    rootDirectory,
+    preferredRevision,
+    isPuppeteerCore,
+    product
+  );
+
+  // The introspection in `Helper.installAsyncStackHooks` references `Puppeteer._launcher`
+  // before the Puppeteer ctor is called, such that an invalid Launcher is selected at import,
+  // so we reset it.
+  puppeteer._lazyLauncher = undefined;
+  return puppeteer;
+};