docs: Functions ESM Sample (GoogleCloudPlatform#315)

docs: add docs for esm support

Signed-off-by: Grant Timmerman <[email protected]>

Author: grant

.eslintignore

@@ -1,3 +1,4 @@
 **/node_modules
 build/
 test/data/esm_*
+docs/

docs/README.md

@@ -6,7 +6,7 @@ This directory contains advanced docs around the Functions Framework.
 - [Debugging Functions](debugging.md)
 - [Running and Deploying Docker Containers](docker.md)
 - [Writing a Function in Typescript](typescript.md)
-- [ES Modules](esm.md)
+- [ES Modules](esm/README.md)
 
 ## TODO Docs
 

docs/esm/README.md

@@ -0,0 +1,59 @@
+# Using ES Modules
+
+The Functions Framework >= `1.9.0` supports loading your code as an ES Module.
+
+ECMAScript modules (ES modules or ESM) are a TC39 standard, unflagged feature in Node >=14 for loading JavaScript modules. As opposed to CommonJS, ESM provides an asynchronous API for loading modules and provides a very commonly adopted syntax improvement via `import` and `export` statements.
+
+## Example
+
+Before:
+
+```js
+exports.helloGET = (req, res) => {
+ res.send('No ESM.');
+};
+```
+
+After:
+
+```js
+export const helloGET = (req, res) => {
+ res.send('ESM!');
+};
+```
+
+## Quickstart
+
+<img src="https://avatars2.githubusercontent.com/u/2810941?v=3&s=96" alt="Google Cloud Platform logo" title="Google Cloud Platform" align="right" height="96" width="96"/>
+
+Create a `package.json` file:
+
+```json
+{
+  "type": "module",
+  "scripts": {
+    "start": "functions-framework --target=helloGET"
+  },
+  "main": "index.js",
+  "dependencies": {
+    "@google-cloud/functions-framework": "^1.9.0"
+  }
+}
+```
+
+Create a `index.js` file:
+
+```js
+export const helloGET = (req, res) => {
+  res.send('ESM!');
+};
+```
+
+Install dependencies and start the framework:
+
+```sh
+npm i
+npm start
+```
+
+Go to `localhost:8080/` and see your function execute!

docs/esm/consts.js

@@ -0,0 +1,17 @@
+// Copyright 2021 Google LLC
+//
+// 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.
+
+// [START functions_esm_const]
+export const MY_CONST = 'ESM';
+// [END functions_esm_const]

docs/esm/index.js

@@ -0,0 +1,21 @@
+// Copyright 2021 Google LLC
+//
+// 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.
+
+// [START functions_esm]
+import {MY_CONST} from './consts.js';
+
+export const esm = (req, res) => {
+  res.send(`Hello, ${MY_CONST}!`);
+};
+// [END functions_esm]