JSFiddle - React, Tailwind, and code Playground

by Stas Orekhovskiy

HTML

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Function library example</title>
  <style>
    input {
      font-size: 2em;
      margin: 10px 1px 0;
    }
  </style>
</head>
<body>

  <input class="numberInput" type="text">
  <p></p>
  
  <script>
    var input = document.querySelector('.numberInput');
    var para = document.querySelector('p');
    
    function squared(num) {
      return num * num;
    }

    function cubed(num) {
      return num * num * num;
    }

    function factorial(num) {
      var x = num;
      while (x > 1) {
        num *= x-1;
        x--;
      }
      return num;
    }
    
    input.onchange = function() {
    var num = input.value;
    if (isNaN(num)) {
      para.textContent = 'You need to enter a number!';
    } else {
      para.textContent = num + ' squared is ' + squared(num) + '. ' +
                         num + ' cubed is ' + cubed(num) + '. ' +
                         num + ' factorial is ' + factorial(num) + '.';
    }
  }
  </script>
</body>
</html>