React - setState 不更新值 [英] React - setState does not update the value

问题描述

我正在尝试使用 DidMount 中的 localStorage 值更新状态，但它没有更新:

I am trying to update the state with a localStorage value in DidMount, but it is not updating:

type Props = {
};

type State = {
    id_evaluation: string,
};

class Evaluation extends Component < Props, State > {
    state = {
        id_evaluation: '',
    }

    componentDidMount() {
        const id_eval = getEvaluation();
        console.log('1 - ', id_eval)

        this.setState({
            id_evaluation: '1',
        });

        console.log('2 - ', this.state.id_evaluation)

在第一个 console.log 中，我的值为 1，在第二个中它保持为空，不更新状态.

In the first console.log I have the value 1, in the second it remains empty, it does not update the state.

推荐答案

this.setState 是一个异步函数.

this.setState is an async function.

 this.setState({
        id_evaluation: '1',
 }, () => console.log('2 - ', this.state.id_evaluation));

回调函数可以解决您的问题.

Callback function would solve your problem.

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