React hooks useeffect

React useEffect

import React, { useEffect } from 'react';

export const App: React.FC = () => {
  
  useEffect(() => {
        
  }, [/*Here can enter some value to call again the content inside useEffect*/])
  
  return (
    <div>Use Effect!</div>
  );
}

Useeffect with cleanup

  useEffect(() => {
	//your code goes here
    return () => {
      //your cleanup code codes here
    };
  },[]);

How to use useeffect

import React, { useState, useEffect } from 'react';
function Example() {
  const [count, setCount] = useState(0);

  // Similar to componentDidMount and componentDidUpdate:  
  useEffect(() => {    
  	// Update the document title using the browser API    
  	document.title = `You clicked ${count} times`;  
  });
  
  return (
    <div>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click me
      </button>
    </div>
  );
}

Source: reactjs.org

What is useeffect

useEffect is a hook for encapsulating code that has 'side effects,' and is like a combination of componentDidMount , componentDidUpdate , and componentWillUnmount . Previously, functional components didn't have access to the component life cycle, but with useEffect you can tap into it.23.1.2019

Componentwillunmount hooks

useEffect(() => {
  window.addEventListener('mousemove', () => {});

  // returned function will be called on component unmount 
  return () => {
    window.removeEventListener('mousemove', () => {})
  }
}, [])

Source: stackoverflow.com

React hooks useeffect

jsximport { useEffect, useState } from 'react';function MyComponent({ prop }) {  const [state, setState] = useState('');  useEffect(() => {    // Runs ONCE after initial rendering    // and after every rendering ONLY IF `prop` or `state` changes  }, [prop, state]);}

Source: dmitripavlutin.com

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