Are PASTE events asynchronous? What is the best way to handle this?

Question

Recently, I noticed a strange behaviour of paste events: the value of an input element is updated after the function is triggered! If you just pass to the function the value itself or event.target.value, the function gets an old input value; the only workaround I found is to set a timeout and process event.target.value after some small random time when the input value is already updated. Is there perhaps some better solution (e.g., somethig like event.oncomplete that would allow to use the Promise API and resolve a promise after a paste operation is complete and the value of an input element is already updated?

Below is a runnable demo code snippet that shows the situation – if no timeout is set, the input element value is evaluated and changed by the function before pasting is complete:

function alertValue({ target: t }) {
  const [run, delay] = [() => {
    alert(`The value is: "${t.value}".`);
    t.value = '';
  }, document.getElementById('sel').value];
  delay ? setTimeout(run, 10) : run();
}

<h1>Paste event demo</h1>
<select id="sel">
  <option value="">Without timeout</option>
  <option value="1">WITH timeout</option>
</select><br>
<label>Paste something here:</label><br>
<input type="text" onpaste="alertValue(event)">