React: is not defined no-undef

Question

When I refresh the error message in clearAll() is:

./src/App.js

Line 22: 'notes' is not defined no-undef

Line 23: 'notes' is not defined no-undef

How do I define the the properties to use>

import React, { Component } from 'react';
import Route from 'react-router-dom';
import './App.css';
import Header from './components/Header';
import Router from './components/Router';
import Home from '.Home';
import AddNote from '/AddNote';
import EditNote from '/EditNote';


class App extends React.Component {

constructor(props) {
    super(props);
    this.state = {
        note: "",
        notes: []
    };
}

clearAll() {
    notes.length = 0;
    notes = [];
}

Answer 1

Here you are trying to update your state variable. For that you can use setState function.
https://reactjs.org/docs/react-component.html#setstate
http://www.cluemediator.com/state-react-js/

You clearAll function should be look like below.

constructor(props) {
    super(props);
    this.state = {
        note: "",
        notes: []
    };
    this.clearAll = this.clearAll.bind(this);
}

clearAll() {
   this.setState({notes: []});
}

Hope this will work for you!

Answer 2

note和notes保存在组件的 state 中，您可以分别通过this.state.note和this.state.notes在组件中访问它们。

Answer 3

const { note, notes } = this.state;