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

0 vote362 views1 answer
React call component state
Javascript React
0 vote342 views2 answers
React firebase hooks
Javascript React
0 vote273 views2 answers
React refresh page not found
Javascript React
0 vote308 views3 answers
How to use keyextractor in flatlist react native
Javascript React
0 vote375 views1 answer
Center child components in react
Javascript React
0 vote354 views2 answers
Add typescript to react-native
Javascript React
0 vote359 views1 answer
Using shortid in react lists
Javascript React
0 vote344 views1 answer
Dropdown list value react fragment
Javascript React
0 vote402 views1 answer
Display only initials from full name reactjs
Javascript React
3 votes370 views3 answers
React change url params
Javascript React