Why is this null?
class App extends Component {
handleClick(e) {
console.log(this)//为什么是 null？
}
render() {
return (
<h2 onClick={this.handleClick}>React</h2>
);
}
}
export default App;
How to explain the following situation?
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<button onclick="func()">click</button> // 打印 undefined
<button onclick="app.handleClick()">click</button> // 打印 App
<script>
class App {
handleClick() {
console.log(this)
}
}
const app = new App
const func = app.handleClick
</script>
</body>
</html>
So when will undefined be printed, when will null be printed, and when will it be printed normally?
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