<input type="text" id="autocomplete" list="options">
<datalist id="options">
  <option value="https://www.example.com">Example</option>
  <option value="https://www.google.com">Google</option>
  <option value="https://www.github.com">GitHub</option>
</datalist>

<a id="link" href="#">Link</a>

<script>
  const autocompleteInput = document.getElementById('autocomplete');
  const link = document.getElementById('link');

  autocompleteInput.addEventListener('input', function() {
    link.href = autocompleteInput.value;
  });
</script>