react native change state code example

Example 1: how to use setstate

class App extends React.Component {

state = { count: 0 }

handleIncrement = () => {
  this.setState({ count: this.state.count + 1 })
}

handleDecrement = () => {
  this.setState({ count: this.state.count - 1 })
}
  render() {
    return (
      <div>
        <div>
          {this.state.count}
        </div>
        <button onClick={this.handleIncrement}>Increment by 1</button>
        <button onClick={this.handleDecrement}>Decrement by 1</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});