Seamlessly sync examples from Github -> Codepen

.eslintignore

@@ -4,4 +4,7 @@ node_modules/*
 content/*
 
 # Ignore built files
-public/*
+public/*
+
+# Ignore examples
+examples/*

content/docs/hello-world.md

@@ -11,7 +11,7 @@ redirect_from:
   - "docs/getting-started-zh-CN.html"
 ---
 
-The easiest way to get started with React is to use [this Hello World example code on CodePen](http://codepen.io/gaearon/pen/ZpvBNJ?editors=0010). You don't need to install anything; you can just open it in another tab and follow along as we go through examples. If you'd rather use a local development environment, check out the [Installation](/docs/installation.html) page.
+The easiest way to get started with React is to use <a href="/examples/hello-world" target="_blank">this Hello World example code on CodePen</a>. You don't need to install anything; you can just open it in another tab and follow along as we go through examples. If you'd rather use a local development environment, check out the [Installation](/docs/installation.html) page.
 
 The smallest React example looks like this:
 

content/docs/introducing-jsx.md

@@ -46,7 +46,7 @@ ReactDOM.render(
 );
 ```
 
-[Try it on CodePen.](http://codepen.io/gaearon/pen/PGEjdG?editors=0010)
+<a href="/examples/introducing-jsx" target="_blank">Try it on CodePen.</a>
 
 We split JSX over multiple lines for readability. While it isn't required, when doing this, we also recommend wrapping it in parentheses to avoid the pitfalls of [automatic semicolon insertion](http://stackoverflow.com/q/2846283).
 

examples/hello-world.js

@@ -0,0 +1,4 @@
+ReactDOM.render(
+  <h1>Hello, world!</h1>,
+  document.getElementById('root')
+);

examples/index.html

@@ -0,0 +1,3 @@
+<div id="root">
+  <!-- This div's content will be managed by React. -->
+</div>

examples/introducing-jsx.js

@@ -0,0 +1,19 @@
+function formatName(user) {
+  return user.firstName + ' ' + user.lastName;
+}
+
+const user = {
+  firstName: 'Harper',
+  lastName: 'Perez',
+};
+
+const element = (
+  <h1>
+    Hello, {formatName(user)}!
+  </h1>
+);
+
+ReactDOM.render(
+  element,
+  document.getElementById('root')
+);

gatsby-node.js

@@ -8,6 +8,7 @@
 
 const {resolve} = require('path');
 const webpack = require('webpack');
+const fs = require('fs');
 
 exports.modifyWebpackConfig = ({config, stage}) => {
   // See https://github.com/FormidableLabs/react-live/issues/5
@@ -74,11 +75,11 @@ exports.createPages = async ({graphql, boundActionCreators}) => {
       // (which gets created by Gatsby during a separate phase).
     } else if (
       slug.includes('blog/') ||
-      slug.includes('community/') ||
-      slug.includes('contributing/') ||
-      slug.includes('docs/') ||
-      slug.includes('tutorial/') ||
-      slug.includes('warnings/')
+            slug.includes('community/') ||
+            slug.includes('contributing/') ||
+            slug.includes('docs/') ||
+            slug.includes('tutorial/') ||
+            slug.includes('warnings/')
     ) {
       let template;
       if (slug.includes('blog/')) {
@@ -87,8 +88,8 @@ exports.createPages = async ({graphql, boundActionCreators}) => {
         template = communityTemplate;
       } else if (
         slug.includes('contributing/') ||
-        slug.includes('docs/') ||
-        slug.includes('warnings/')
+                slug.includes('docs/') ||
+                slug.includes('warnings/')
       ) {
         template = docsTemplate;
       } else if (slug.includes('tutorial/')) {
@@ -117,8 +118,8 @@ exports.createPages = async ({graphql, boundActionCreators}) => {
         redirect.forEach(fromPath => {
           if (redirectToSlugMap[fromPath] != null) {
             console.error(`Duplicate redirect detected from "${fromPath}" to:\n` +
-              `* ${redirectToSlugMap[fromPath]}\n` +
-              `* ${slug}\n`
+                            `* ${redirectToSlugMap[fromPath]}\n` +
+                            `* ${slug}\n`
             );
             process.exit(1);
           }
@@ -161,6 +162,29 @@ exports.createPages = async ({graphql, boundActionCreators}) => {
     redirectInBrowser: true,
     toPath: newestBlogNode.fields.slug,
   });
+
+  // Create Codepen example pages
+  const htmlTemplate = fs.readFileSync('./examples/index.html', 'utf8');
+  fs.readdirSync('./examples').forEach(file => {
+    // Only create pages for the JS files
+    if (file.toLowerCase().split('.').pop() === 'js') {
+      const slug = file.substring(0, file.length - 3);
+      const jsTemplate = fs.readFileSync(`./examples/${file}`, 'utf8');
+
+      createPage({
+        path: `/examples/${slug}`,
+        component: resolve('./src/templates/codepen-example.js'),
+        context: {
+          slug,
+          payload: {
+            html: htmlTemplate,
+            js: jsTemplate,
+          },
+        },
+      });
+    }
+  });
+
 };
 
 // Parse date information out of blog post filename.

package.json

@@ -84,4 +84,4 @@
   "devDependencies": {
     "eslint-config-prettier": "^2.6.0"
   }
-}
+}

src/templates/codepen-example.js

@@ -0,0 +1,64 @@
+'use strict';
+
+import React, {Component} from 'react';
+import Container from 'components/Container';
+import {colors} from 'theme';
+// import {version} from '../site-constants';
+
+// Copied over styles from ButtonLink for the submit btn
+const primaryStyle = {
+  backgroundColor: colors.brand,
+  color: colors.black,
+  padding: '10px 25px',
+  whiteSpace: 'nowrap',
+  transition: 'background-color 0.2s ease-out',
+  outline: 0,
+  border: 'none',
+  cursor: 'pointer',
+
+  ':hover': {
+    backgroundColor: colors.white,
+  },
+
+  display: 'inline-block',
+  fontSize: 16,
+};
+
+class CodepenExample extends Component {
+  componentDidMount() {
+    this.codepenForm.submit();
+  }
+
+  render() {
+    const {payload} = this.props.pathContext;
+    // Set codepen options
+    payload.js_pre_processor = 'babel';
+    // Only have the JS editor open (default for all examples)
+    payload.editors = '0010';
+    // We can pass @version in the URL for version locking, if desired.
+    payload.js_external = `https://unpkg.com/react/umd/react.development.js;https://unpkg.com/react-dom/umd/react-dom.development.js`;
+
+    return (
+      <Container>
+        <h1>Redirecting to Codepen...</h1>
+        <form
+          style={{paddingBottom: '50px'}}
+          ref={form => {
+            this.codepenForm = form;
+          }}
+          action="https://codepen.io/pen/define"
+          method="POST">
+          <input type="hidden" name="data" value={JSON.stringify(payload)} />
+
+          <input
+            style={primaryStyle}
+            type="submit"
+            value="Not automatically redirecting? Click here."
+          />
+        </form>
+      </Container>
+    );
+  }
+}
+
+export default CodepenExample;