如何在 React JS 中 5 秒后消失警报？

Question

import { useState } from 'react'
    
    const Message = ({ variant, children }) => {
      const [timeOut, setTimeOut] = useState(null)
    
      setTimeout(() => {
        setTimeOut(1)
      }, 3000)
    
      return (
        timeOut !== 1 && <div className={`alert alert-${variant}`}>{children}</div>
      )
    }
    
    Message.defaultPros = {
      variant: 'info',
    }
    
    export default Message

我想在 2 或 3 秒后消失此警报。我使用了这个逻辑，它很好并且可以工作，但是在我的控制台中，我收到了这个警告：

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.

它会影响我的应用程序还是没问题？你可以给我一个更好的想法来实现这个逻辑。

Answer 1

这将在 3 秒内显示警报，然后它将消失：

import React, { useEffect, useState } from 'react';

const Message = ({ variant, children }) => {
  // the alert is displayed by default
  const [alert, setAlert] = useState(true);
      
  useEffect(() => {
    // when the component is mounted, the alert is displayed for 3 seconds
    setTimeout(() => {
      setAlert(false);
    }, 3000);
  }, []);     
    
  return (
    {alert && <div className={`alert alert-${variant}`}>{children}</div>}
  )
}

Answer 2

大家可以看看评论

import { useState, useEffect } from 'react'
    
const Message = ({ variant, children }) => {
  const [show, setShow] = useState(true)

  // On componentDidMount set the timer
  useEffect(() => {
    const timeId = setTimeout(() => {
      // After 3 seconds set the show value to false
      setShow(false)
    }, 3000)

    return () => {
      clearTimeout(timeId)
    }
  }, []);

  // If show is false the component will return null and stop here
  if (!show) {
    return null;
  }

  // If show is true this will be returned
  return (
    <div className={`alert alert-${variant}`}>
      {children}
    </div>
  )
}

Message.defaultPros = {
  variant: 'info',
}

export default Message;

Answer 3

import React, { useEffect, useState } from 'react';

const Message = ({ variant, children }) => {

  const [alert, setAlert] = useState(true);
      
  useEffect(() => {
    const timer = setTimeout(() => {
      setAlert(false);
    }, 3000);
    
    // To clear or cancel a timer, you call the clearTimeout(); method, 
    // passing in the timer object that you created into clearTimeout().
    
    return () => clearTimeout(timer);
  }, []);     
    
  return (
    {alert && <div className={`alert alert-${variant}`}>{children}</div>}
  )
}

如何在 React JS 中 5 秒后消失警报？

How to disappear alert after 5 seconds in React JS?

javascript

reactjs

react-bootstrap