onpressIn.js

constructor() {
    super();
    this.state = {
      number: 0,
    };
    this.timer = null;
    this.addOne = this.addOne.bind(this);
    this.stopTimer = this.stopTimer.bind(this);
  }

  addOne() {
    this.setState({number: this.state.number+1});
    this.timer = setTimeout(this.addOne, 200);
  }

  stopTimer() {
    clearTimeout(this.timer);
  }