JSFiddle - React, Tailwind, and code Playground

by André Albson

HTML

<select multiple="multiple" name="remaintextarea" id="studentremain" size="10">
    <option value="one">One</option>
    <option value="two">Two</option>
    <option value="three">Three</option>
</select>
<button type='button' id='selectall'>Select All</button>
<button type='button' id='deselectall'>De-Select All</button>

JavaScript

$('#selectall').click(function() {
    $('#studentremain > option').attr("selected", "selected");
});   

$('#deselectall').click(function() {
    $('#studentremain > option').removeAttr("selected");
});