React hooks

Usestate hook

import React, { useState } from 'react';

function Example() {
  // Declare a new state variable, which we'll call "count"  
  const [count, setCount] = useState(0);
  return (
    <div>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click me
      </button>
    </div>
  );
}

Source: reactjs.org

React Hooks

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

function FriendStatus(props) {
  const [isOnline, setIsOnline] = useState(null);  useEffect(() => {    function handleStatusChange(status) {      setIsOnline(status.isOnline);    }    ChatAPI.subscribeToFriendStatus(props.friend.id, handleStatusChange);    return () => {      ChatAPI.unsubscribeFromFriendStatus(props.friend.id, handleStatusChange);    };  });
  if (isOnline === null) {
    return 'Loading...';
  }
  return isOnline ? 'Online' : 'Offline';
}

Source: reactjs.org

React hooks

function ExampleWithManyStates() {
  // Declare multiple state variables!
  const [age, setAge] = useState(42);
  const [fruit, setFruit] = useState('banana');
  const [todos, setTodos] = useState([{ text: 'Learn Hooks' }]);
  // ...
}

Source: reactjs.org

React hooks

componentDidUpdate(prevProps, prevState) {
  if (prevState.count !== this.state.count) {
    document.title = `You clicked ${this.state.count} times`;
  }
}

-3

Source: reactjs.org

Similar codes

3 votes124 views3 answers
React hide source code
Javascript React
0 vote149 views1 answer
How to submit form in reactjs and send data in json
Javascript React
47 votes132 views3 answers
How to comment in the react javascript
Javascript React
0 vote170 views1 answer
React js marked import and use
Javascript React
4 votes126 views1 answer
Import react icons module
Javascript React
0 vote129 views1 answer
React native run real device
Javascript React
5 votes140 views2 answers
React onclick new tab
Javascript React
22 votes131 views3 answers
How to use if else inside jsx in react
Javascript React
59 votes135 views3 answers
Npm react router dom
Javascript React
1 vote89 views1 answer
Mkdir: cannot create directory â€˜src/components/dashboardâ€™: no such file or directory in react
Javascript React