HTML select drop-down with an input field [duplicate]

You can use input text with "list" attribute, which refers to the datalist of values.

<input type="text" name="city" list="cityname">
    <datalist id="cityname">
      <option value="Boston">
      <option value="Cambridge">
    </datalist>

This creates a free text input field that also has a drop-down to select predefined choices. Attribution for example and more information: https://www.w3.org/wiki/HTML/Elements/datalist