Update QuickStart-API-Basics.md (#2491)

Summary: Pull Request resolved: #2491

Reviewed By: elboman

Differential Revision: D22788091

Pulled By: mrkev

fbshipit-source-id: c83b95a355f0aecfaf6f5ed35a4fdde3b4fbe05a

docs/QuickStart-API-Basics.md

@@ -19,20 +19,16 @@ As a brief refresher, controlled inputs involve two key pieces:
 2. An _onChange_ prop function to receive updates to the input
 
 This approach allows the component that composes the input to have strict
-control over the state of the input, while still allowing updates to the DOM
-to provide information about the text that the user has written.
+control over the state of the input, while still allowing updates to the DOM to
+provide information about the text that the user has written.
 
 ```js
-class MyInput extends React.Component {
-  constructor(props) {
-    super(props);
-    this.state = {value: ''};
-    this.onChange = evt => this.setState({value: evt.target.value});
-  }
-  render() {
-    return <input value={this.state.value} onChange={this.onChange} />;
-  }
-}
+const MyInput = () => {
+  const [value, setValue] = useState('');
+  const onChange = (evt) => setValue(evt.target.value);
+
+  return <input value={value} onChange={onChange} />;
+};
 ```
 
 The top-level component can maintain control over the input state via this
@@ -42,13 +38,14 @@ The top-level component can maintain control over the input state via this
 
 In a React rich text scenario, however, there are two clear problems:
 
-1. A string of plaintext is insufficient to represent the complex state of a rich editor.
+1. A string of plaintext is insufficient to represent the complex state of a
+   rich editor.
 2. There is no such `onChange` event available for a ContentEditable element.
 
 State is therefore represented as a single immutable
-[EditorState](/docs/api-reference-editor-state) object, and
-`onChange` is implemented within the `Editor` core to provide this state
-value to the top level.
+[EditorState](/docs/api-reference-editor-state) object, and `onChange` is
+implemented within the `Editor` core to provide this state value to the top
+level.
 
 The `EditorState` object is a complete snapshot of the state of the editor,
 including contents, cursor, and undo/redo history. All changes to content and
@@ -58,19 +55,15 @@ this remains efficient due to data persistence across immutable objects.
 ```js
 import {Editor, EditorState} from 'draft-js';
 
-class MyEditor extends React.Component {
-  constructor(props) {
-    super(props);
-    this.state = {editorState: EditorState.createEmpty()};
-    this.onChange = editorState => this.setState({editorState});
-  }
-
-  render() {
-    return (
-      <Editor editorState={this.state.editorState} onChange={this.onChange} />
-    );
-  }
-}
+const MyInput = () => {
+  const [editorState, setEditorState] = useState(() =>
+    EditorState.createEmpty(),
+  );
+
+  return <Editor editorState={editorState} onChange={setEditorState} />;
+};
 ```
 
-For any edits or selection changes that occur in the editor DOM, your `onChange` handler will execute with the latest `EditorState` object based on those changes.
+For any edits or selection changes that occur in the editor DOM, your `onChange`
+handler will execute with the latest `EditorState` object based on those
+changes.