JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://underscorejs.org/underscore.js"></script>
<form name="fsnotes">
    <textarea rows="8" cols="50" name="notesentry"></textarea>
    </br>
    <select name="caller">
        <option>CH</option>
    </select>
    <button onClick="openCall(); return false;">OK</button>
</form>

JavaScript

function openCall() {
    var callerselection = document.fsnotes.caller.value;
    if (callerselection == "CH") {
        document.fsnotes.notesentry.value += "CH called ";
    }
}