从道具“ReactJs JavaScript”中获取值

Question

我从道具中获取以下值时遇到问题，这是一个截图：

const files = updatedValue.files;

const firstName = updatedValue.firstName;

const lastname = updatedValue.lastname;

onChange = updatedValue => {


const files = updatedValue.files;
const firstName = updatedValue.firstName;
const lastname = updatedValue.lastname;

//I need to use the values here 


};

render() {
return (
<div className="App">
<Form onChange={fields => this.onChange(fields)} />
<p>

</p>
</div>

Answer 1

import React, { Component } from 'react';
import './App.css';

class App extends Component {
  state = {
    user: {
      firstName: "",
      lastName: "",
      files: []
    }
  }

  handleClick = e => {
    this.setState({firstName: "Sample", lastName:"Test"}, () => {
      console.log(`${this.state.firstName} ${this.state.lastName}`)
      // output will be Sample Test
    })

  }

  render() {
    return (
      <div>
       <button onClick={this.handleClick}>Sample Button</button>
      </div>
    );
  }
}

export default App;

SetState是一个异步，你可以看看这个set State async !!