javascript - setState 的回调是否在(同步)状态设置后发生？

Question

我有一个表单选择，其值为“更改”和“取消”。 每次我选择不同的一个时，我都会console.log“mySelection”的值

handleSelectChange = e => {
    var myValue = e.target.value
    if (myValue == "change"){
        this.setState({selectText: "Change rent date"})
        this.setState({selection: "sdsd"})
        this.setState({mySelection: "change" }, console.log(this.state.mySelection))
    }
    if (myValue == "cancel"){
        this.setState({selectText: "Cancel a rent"})
        this.setState({selection: "bob"})
        this.setState({mySelection: "cancel"  }, console.log(this.state.mySelection))
    }
}

当我选择更改时，它控制台记录取消。当我选择取消时，它控制台记录更改。我以为setState的回调是在状态设置之后发生的？

谢谢

Answer 1

您必须传递一个函数作为setState的第二个参数

handleSelectChange = e => {
    var myValue = e.target.value
    if (myValue == "change"){
        this.setState({selectText: "Change rent date"})
        this.setState({selection: "sdsd"})
        this.setState({mySelection: "change" }, () => console.log(this.state.mySelection))
    }
    if (myValue == "cancel"){
        this.setState({selectText: "Cancel a rent"})
        this.setState({selection: "bob"})
        this.setState({mySelection: "cancel"  }, () => console.log(this.state.mySelection))
    }
}