React - uncaught TypeError：无法读取undefined的属性

Question

React - uncaught TypeError：无法读取undefined的属性'setState'

我收到以下错误

未捕获的TypeError：无法读取未定义的属性“setState”

甚至在构造函数中绑定delta之后。

class Counter extends React.Component {
    constructor(props) {
        super(props);

        this.state = {
            count : 1
        };

        this.delta.bind(this);
    }

    delta() {
        this.setState({
            count : this.state.count++
        });
    }

    render() {
        return (
            <div>
                <h1>{this.state.count}</h1>
                <button onClick={this.delta}>+</button>
            </div>
        );
    }}