Type here:
<input class="FormControl" id="input1" />
<br>
Cloned here:
<textarea class="Preview"></textarea>
document.querySelector(".FormControl").addEventListener('keyup', copyToDiv);

function copyToDiv() {
  document.querySelector("textarea").innerHTML = document.querySelector(".FormControl").value;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.