javascript - 在我的应用程序中设置状态时如何修复内存泄漏
问题描述
我目前正在开发一个音乐应用程序,并且在离开详细信息页面时遇到内存泄漏错误消息。
当我使用后退按钮导航回我的主页时,我在控制台中收到此错误消息。
index.js:1 Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.
我该如何解决?过去在使用 React 时,我不必处理任何代码清理。
ConcertDetails.js
import React, { useState, useEffect } from 'react';
import axios from '../utils/API';
const ConcertDetails = (Props) => {
const [details, setDetails] = useState({});
const [songs, setSongs] = useState([]);
useEffect(() => {
const url = '/concerts/' + Props.match.params.id.toString() + '/';
const getDetails = async () => {
const response = await axios.get(url, {}, {'Content-Type': 'application/json'});
setDetails(response.data);
setSongs(response.data.song);
};
getDetails();
});
const getSongs = () => {
return songs.map((song) => (
<li key={song.title}>{song.title}</li>
));
}
return (
<>
<h1>Concert Details</h1>
<p>Venue: {details.venue}</p>
<p>Date: {details.date}</p>
<ul>
{getSongs()}
</ul>
</>
)
}
export default ConcertDetails;
应用程序.js
import React from 'react';
import './App.css';
import NavBar from "./components/Navbar";
import { BrowserRouter as Router, Switch, Route } from "react-router-dom";
import Home from './pages';
import About from './pages/about';
import Contact from './pages/contact';
import SignUp from './pages/signup';
import SignIn from './pages/signin';
import ConcertDetails from './pages/concertDetails';
function App() {
return (
<Router>
<NavBar />
<Switch>
<Route path="/" exact component={Home} />
<Route path="/about" component={About} />
<Route path="/contact" component={Contact} />
<Route path="/signin" component={SignIn} />
<Route path="/signup" component={SignUp} />
<Route path="/concert/:id" component={ConcertDetails} />
</Switch>
</Router>
);
}
export default App;
解决方案
您只想在第一个组件渲染时运行 useEffect。添加[]
为 useEffect 的第二个参数。
useEffect(() => {
const url = '/concerts/' + Props.match.params.id.toString() + '/';
const getDetails = async () => {
const response = await axios.get(url, {}, {'Content-Type': 'application/json'});
setDetails(response.data);
setSongs(response.data.song);
};
getDetails();
}, []);
没有第二个参数。每次更改状态/道具时都会运行效果。由于效果会改变状态,这可能会导致无限循环。