Merge pull request #64 from reactjs/sync-fa5e6e7a

Sync with reactjs.org @ fa5e6e7

Author: punkah

content/community/conferences.md

@@ -18,15 +18,10 @@ March 30 - 31, 2020 in San Francisco, CA
 [Website](https://www.reactathon.com) - [Twitter](https://twitter.com/reactathon) - [Facebook](https://www.facebook.com/events/575942819854160/)
 
 ### React Summit Amsterdam 2020 {#react-summit-2020}
-April 15-17, 2020 in Amsterdam, The Netherlands
+September 11, 2020 in Amsterdam, The Netherlands
 
 [Website](https://reactsummit.com) - [Twitter](https://twitter.com/reactamsterdam) - [Facebook](https://www.facebook.com/reactamsterdam) - [Videos](https://youtube.com/c/ReactConferences)
 
-### App.js Conf 2020 {#appjsonf2020}
-April 23 - 24, 2020 in Kraków, Poland
-
-[Website](http://appjs.co/react) - [Twitter](https://twitter.com/appjsconf)
-
 ### React Day Bangalore 2020 {#react-day-bangalore-2020}
 April 25, 2020 in Bangalore, India
 

content/docs/code-splitting.md

@@ -97,7 +97,7 @@ import("./math").then(math => {
 When Webpack comes across this syntax, it automatically starts code-splitting
 your app. If you're using Create React App, this is already configured for you
 and you can [start using it](https://facebook.github.io/create-react-app/docs/code-splitting) immediately. It's also supported
-out of the box in [Next.js](https://github.com/zeit/next.js/#dynamic-import).
+out of the box in [Next.js](https://nextjs.org/docs/advanced-features/dynamic-import).
 
 If you're setting up Webpack yourself, you'll probably want to read Webpack's
 [guide on code splitting](https://webpack.js.org/guides/code-splitting/). Your Webpack config should look vaguely [like this](https://gist.github.com/gaearon/ca6e803f5c604d37468b0091d9959269).

content/docs/faq-ajax.md

@@ -82,3 +82,50 @@ class MyComponent extends React.Component {
   }
 }
 ```
+
+Here is the equivalent with [Hooks](https://reactjs.org/docs/hooks-intro.html): 
+
+```js
+function MyComponent() {
+  const [error, setError] = useState(null);
+  const [isLoaded, setIsLoaded] = useState(false);
+  const [items, setItems] = useState([]);
+
+  // Note: the empty deps array [] means
+  // this useEffect will run once
+  // similar to componentDidMount()
+  useEffect(() => {
+    fetch("https://api.example.com/items")
+      .then(res => res.json())
+      .then(
+        (result) => {
+          setIsLoaded(true);
+          setItems(result.items);
+        },
+        // Note: it's important to handle errors here
+        // instead of a catch() block so that we don't swallow
+        // exceptions from actual bugs in components.
+        (error) => {
+          setIsLoaded(true);
+          setError(error);
+        }
+      )
+  }, [])
+
+  if (error) {
+    return <div>Error: {error.message}</div>;
+  } else if (!isLoaded) {
+    return <div>Loading...</div>;
+  } else {
+    return (
+      <ul>
+        {items.map(item => (
+          <li key={item.name}>
+            {item.name} {item.price}
+          </li>
+        ))}
+      </ul>
+    );
+  }
+}
+```

content/docs/forms.md

@@ -75,6 +75,7 @@ handleChange(event) {
   this.setState({value: event.target.value.toUpperCase()});
 }
 ```
+Egy kontrollált komponensben a bemenet értékét mindig a React állapot vezérli. Habár ez azt jelenti, hogy egy kicsivel több kódot kell írnod, de így ezt az értéket több komponensnek is át tudod adni, vagy eseménykezelőkből a kezdeti állapotba állítani.
 
 ## A textarea címke {#the-textarea-tag}
 

content/docs/strict-mode.md

@@ -97,13 +97,13 @@ Render phase lifecycles include the following class component methods:
 
 Because the above methods might be called more than once, it's important that they do not contain side-effects. Ignoring this rule can lead to a variety of problems, including memory leaks and invalid application state. Unfortunately, it can be difficult to detect these problems as they can often be [non-deterministic](https://en.wikipedia.org/wiki/Deterministic_algorithm).
 
-Strict mode can't automatically detect side effects for you, but it can help you spot them by making them a little more deterministic. This is done by intentionally double-invoking the following methods:
+Strict mode can't automatically detect side effects for you, but it can help you spot them by making them a little more deterministic. This is done by intentionally double-invoking the following functions:
 
-* Class component `constructor` method
-* The `render` method
-* `setState` updater functions (the first argument)
-* The static `getDerivedStateFromProps` lifecycle
-* The `shouldComponentUpdate` method
+* Class component `constructor`, `render`, and `shouldComponentUpdate` methods
+* Class component static `getDerivedStateFromProps` method
+* Function component bodies
+* State updater functions (the first argument to `setState`)
+* Functions passed to `useState`, `useMemo`, or `useReducer`
 
 > Note:
 >

examples/uncontrolled-components/input-type-file.js

@@ -6,7 +6,7 @@ class FileInput extends React.Component {
     this.fileInput = React.createRef();
   }
   handleSubmit(event) {
-    // highlight-range{4}
+    // highlight-range{3}
     event.preventDefault();
     alert(
       `Selected file - ${this.fileInput.current.files[0].name}`