change state in function react code example

Example 1: usestate in react

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>
  );
}

Example 2: change state in react

import React, {Component} from 'react';

class ButtonCounter extends Component {
  constructor() {
    super()
    // initial state has count set at 0
    this.state = {
      count: 0
    }
  }

  handleClick = () => {
    // when handleClick is called, newCount is set to whatever this.state.count is plus 1 PRIOR to calling this.setState
    let newCount = this.state.count + 1
    this.setState({
      count: newCount
    })
  }

  render() {
    return (
      <div>
        <h1>{this.state.count}</h1>
        <button onClick={this.handleClick}>Click Me</button>
      </div>
    )
  }
}

export default ButtonCounter

Example 3: react change state

// React change state
this.setState({state to change:value});

Example 4: reading state react

<p>You clicked {count} times</p>

Example 5: change state in functional component

const [count, setCount] = useState(0);

setCount(count + 1)