setState 场景题
js
componentDidMount() {
// count 初始值为 0
this.setState({count: this.state.count + 1})
console.log('1', this.state.count) // 0
this.setState({count: this.state.count + 1})
console.log('2', this.state.count) // 0
setTimeout(() => {
this.setState({count: this.state.count + 1})
console.log('3', this.state.count) // 2
})
setTimeout(() => {
this.setState({count: this.state.count + 1})
console.log('4', this.state.count) // 3
})
// 1 0
// 2 0
// 3 2
// 4 3
}