JSFiddle - React, Tailwind, and code Playground

HTML

<select id="test1">
	<option value="a">a</option>
	<option value="b">b</option>
</select>

<select id="test2" onchange="handleSelect(this)">
	<option value="c">c</option>
	<option value="d">d</option>
</select>

JavaScript

document.getElementById("test1").onchange = (e) => {
  console.log(e.value); // undefined
  console.log(e.target.value); // works
}

let handleSelect = (e) => {
  console.log(e.value); // works
  console.log(e.target.value); // e.target is undefined
}