calculator.js

import React, { Component } from 'react';

class Calculator extends Component {

  sleep = (milliseconds) => {
    var start = new Date().getTime();
    for (var i = 0; i < 1e7; i++) {
      if ((new Date().getTime() - start) > milliseconds) {
        break;
      }
    }
  }

  timedOutDisplay = (inputVal) => {
    this.sleep(2000);
    return `Heavy calculation based on input => ${inputVal}`;
  }

  render() {

    return (
      <React.Fragment>
        {this.timedOutDisplay(this.props.inputVal)}
      </React.Fragment>
    );
  }
}

export default Calculator;