JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
 <li><input type="checkbox" ID="check1" checked="checked"/><label for="check1">Monday</label></li>
 <li><input type="checkbox" ID="check2"  checked="checked"/><label for="check2">Tuesday</label></li>
 <li><input type="checkbox" ID="check3"  checked="checked"/><label for="check3">Wednesday</label></li>
 <li><input type="checkbox" ID="check4" checked="checked"/><label for="check4">Thursday</label></li>
</ul>

JavaScript

var str =$('input:checked', 'ul').next().text().replace( /([a-z])([A-Z])/g, "$1AND$2");



alert(str);