JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <input type="file" onchange="CopyMe(this, 'txtFileName');" />
</div>
<div>
    You chose: <input id="txtFileName" type="text" readonly="readonly" />
</div>

JavaScript

function CopyMe(oFileInput, sTargetID) {
    var arrTemp = oFileInput.value.split('\\');
    document.getElementById(sTargetID).value = arrTemp[arrTemp.length - 1];
}