index.html

<input id="my-input" type="text" value="Text">
<button id="clear-button">Clear</button>
<p id="my-p">Text</p>

index.js

var input = document.getElementById('my-input');
var clearButton = document.getElementById('clear-button');
var p = document.getElementById('my-p');

function handleUserInput() {
  p.textContent = input.value;
}

function handleClearClick() {
  p.textContent = '';
  input.value = '';
}

input.addEventListener('input', handleUserInput);
clearButton.addEventListener('click', handleClearClick);