stack.html

<html>
  <head>
    <title>Stack in JavaScript</title>
    <script>
      let data = [];
      let currentSize = data.length;
      let max = 5;
      function push(newVal) {
        if (currentSize >= max) {
          alert("Stack is full you can not add" + newVal);
        }
        data[currentSize] = newVal;
        currentSize += 1;
      }

      function pop() {
        if (currentSize > 0) {
          currentSize -= 1;
          data.length = currentSize;
        } else {
          alert("stack is already empty");
        }
      }

      push(20);
      push(30);
      push(10);
      push(2);
      pop();
      pop();
      pop();
      push(25);
      push(23);
      push(67);
      // pop()
      // pop()

      console.warn(data);
    </script>
  </head>
  <body>
    <h1>Stack in JavaScript</h1>
  </body>
</html>