# 从一道面试题说起
这是一道变体繁多的面试题，在 BAT 等一线大厂的面试中考察频率非常高。首先题目会给出一个这样的 App 组件，在它的内部会有如下代码所示的几个不同的 setState 操作：
import React from "react";
import "./styles.css";
export default class App extends React.Component{
state = {
count: 0
}
increment = () => {
console.log('increment setState前的count', this.state.count)
this.setState({
count: this.state.count + 1
});
console.log('increment setState后的count', this.state.count)
}
triple = () => {
console.log('triple setState前的count', this.state.count)
this.setState({
count: this.state.count + 1
});
this.setState({
count: this.state.count + 1
});
this.setState({
count: this.state.count + 1
});
console.log('triple setState后的count', this.state.count)
}
reduce = () => {
setTimeout(() => {
console.log('reduce setState前的count', this.state.count)
this.setState({
count: this.state.count - 1
});
console.log('reduce setState后的count', this.state.count)
},0);
}
render(){
return <div>
<
