A simple counter, made using React classes and typescript

ClassCounter.tsx

import React, { Component } from "react";

interface Props {
  title: string;
  initialCount: number;
}

interface State {
  count: number;
}

class ClassCounter extends Component<Props, State> {
  state = {
    count: this.props.initialCount
  };

  add = (factor = 1) => {
    const { count } = this.state;
    this.setState({ count: count + factor });
  };

  render() {
    const { title } = this.props;
    const { count } = this.state;

    return (
      <div>
        <h1>{title}</h1>
        <h2>{count}</h2>
        <button onClick={() => this.add()}>+</button>
        <button onClick={() => this.add(-1)}>-</button>
      </div>
    );
  }
}

export default ClassCounter;