我們說setState是批量更新但是下面代碼顯示的star是3有誰知道為什么嗎？import React, { Component } from 'react';class App extends Component {    constructor(props) {        super(props);        this.timer = null;        this.state = { star: 0 };    }        componentDidMount() {        this.timer = setTimeout(() => {            this.setState({ num: this.state.star + 1 });            this.setState({ num: this.state.star + 1 });            this.setState({ num: this.state.star + 1 });        }, 5000);    }        render() {        return <div>{this.state.star}</div>;    }        componentWillUnmount() {        clearTimeout(this.timer);    }}export default App;