Add React 16 note

close #67

Author: yesmeck

HISTORY.md

@@ -5,7 +5,7 @@
 
 - add action `contextMenu`
 
-## 2.0.0
+## 2.0.0 / 2017-09-25
 
 - support React 16
 

README.md

@@ -246,6 +246,64 @@ npm run coverage
 
 open coverage/ dir
 
+## React 16 Note
+
+Note: If you are using React 16, you won't access popup element's ref in parent component's componentDidMount, which means following code won't work.
+
+```javascript
+class App extends React.Component {
+  componentDidMount() {
+    this.input.focus(); // error, this.input is undefined.
+  }
+
+  render() {
+    return (
+      <Trigger
+        action={['click']}
+        popup={<div><input ref={node => this.input = node} type="text" /></div>}
+      >
+        <button>click</button>
+      </Trigger>
+    )
+  }
+}
+```
+
+Consider wrap your popup element to a separate component:
+
+```javascript
+class InputPopup extends React.Component {
+  componentDidMount() {
+    this.onMount();
+  }
+
+  render() {
+    return (
+      <div>
+        <input ref={this.props.inputRef} type="text" />
+      </div>
+    );
+  }
+}
+
+class App extends React.Component {
+  handlePopupMount() {
+    this.input.focus(); // error, this.input is undefined.
+  }
+
+  render() {
+    return (
+      <Trigger
+        action={['click']}
+        popup={<InputPopup inputRef={node => this.input = node} onMount={this.handlePopupMount} />}
+      >
+        <button>click</button>
+      </Trigger>
+    )
+  }
+}
+```
+
 ## License
 
 rc-trigger is released under the MIT license.