HTML supports autocomplete-style dropdowns

HTML has native support for autocomplete-style dropdowns attached to inputs via the <datalist> element.

This input behaves like a <select> but you can type text in it and choose a specific value.

Source: @tejaskumar_

<input list="beatles" placeholder="Start typing...">
<datalist id="beatles">
	<option value="John">
	<option value="Yoko">
	<option value="Paul">
	<option value="George">
	<option value="Ringo">
	<option value="Pete">
</datalist>

See list points to id of datalist.