In a Windows Forms application, a drop-down selector list also gives the user the option of typing an alternate value into that same field (assuming the developer has left this option enabled on the control.)
How does one accomplish this in HTML? It appears as if it is only possible to select values from the list.
If it's not possible to do this with straight HTML, is there a way to do this with Javascript?
It can be done now with HTML5
See this post here HTML select form with option to enter custom value
<input type="text" list="cars" />
<datalist id="cars">
<option>Volvo</option>
<option>Saab</option>
<option>Mercedes</option>
<option>Audi</option>
</datalist>