[英]set value to state in React
I am new to React, and I have a question of set state, this is the code:我是 React 的新手,我有一个问题集 state,这是代码:
this.setState((prevState) => {
return{
prevVal: prevState.currentVal,
currentVal: 'DIGIT LIMIT MET'
}
});
In this code, the prevVal in my project will be updated to 'DIGIT LIMIT MET' , but I want it to be the last currentVal which is prevState.currentVal.在此代码中,我项目中的prevVal将更新为'DIGIT LIMIT MET' ,但我希望它是最后一个currentVal ,即 prevState.currentVal。
this.setState({
prevVal: this.state.currentVal,
currentVal: 'DIGIT LIMIT MET'
});
In this code, the problem will not appear, but according to React document, it can not make sure that the this.state.currentVal is the prevState.currentVal.在这段代码中,不会出现这个问题,但是根据React文档,无法确定this.state.currentVal就是prevState.currentVal。
How to solve this problem perfectly?如何完美解决这个问题? Am I misunderstanding something?
我误会了什么吗?
this.setState(
prevState => {
const prev = prevState.currentVal;
return {
prevVal: prev,
currentVal: 'DIGIT LIMIT MET'
};
},
() => console.log(this.state)
);
try this.尝试这个。
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