JSFiddle - React, Tailwind, and code Playground

HTML

<input></input>
<select id="selectionList">
    <option>1</option>
    <option>2</option>
    <option>3</option>
</select>

JavaScript

// Option 1
$('#selectionList').focus(function(event) {
   event.target.size = $('#selectionList').children().length; 
});

$('#selectionList').blur(function(event) {
   event.target.size = 1;
});