freeCodeCamp Challenge Guide: Write a Simple Counter

Write a Simple Counter


Hints

Hint 1

class Counter extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      count: 0
    };
    // change code below this line
         // Remember the previous challange. 
         // Bind "this" for each of these three method (increment(),decrement() and reset()).
    // change code above this line
  }
  // change code below this line
         // Define these three method here.
         // Inside these methods, call "setState()" method to update the data of construtor`s state. 
  // change code above this line
  render() {
    return (
      <div>
        <button className='inc' onClick={this.increment}>Increment!</button>
        <button className='dec' onClick={this.decrement}>Decrement!</button>
        <button className='reset' onClick={this.reset}>Reset</button>
        <h1>Current Count: {this.state.count}</h1>
      </div>
    );
  }
};

Solutions

Solution 1 (Click to Show/Hide)
class Counter extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      count: 0
    };
  this.increment = this.increment.bind(this);
  this.decrement = this.decrement.bind(this);
  this.reset = this.reset.bind(this);
 }
  reset() {
    this.setState({
      count: 0
    });
  }
  increment() {
    this.setState(state => ({
      count: state.count + 1
    }));
  }
  decrement() {
    this.setState(state => ({
      count: state.count - 1
    }));
  }
  render() {
    return (
      <div>
        <button className='inc' onClick={this.increment}>Increment!</button>
        <button className='dec' onClick={this.decrement}>Decrement!</button>
        <button className='reset' onClick={this.reset}>Reset</button>
        <h1>Current Count: {this.state.count}</h1>
      </div>
    );
  }
};
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