how to link the value you inputed in textfield to drop down list code example

Example: textbox dropdown with manual input

<label>Choose a browser from this list:
<input list="browsers" name="myBrowser" /></label>
<datalist id="browsers">
  <option value="Chrome">
  <option value="Firefox">
  <option value="Internet Explorer">
  <option value="Opera">
  <option value="Safari">
  <option value="Microsoft Edge">
</datalist>