JSFiddle - React, Tailwind, and code Playground

HTML

<li>
<input id="mem3" value="TestU4" disabled="">
<button id="del3" class="delmem" onclick="deleteBandMember(this);">remove</button>
</li>

JavaScript

function deleteBandMember(elem){
   var mmbr = $(elem).prev("input").val();
    alert(mmbr)
}