JSFiddle - React, Tailwind, and code Playground
HTML
<input id="EI_InitialTests_AnalysisPressure" type="text" size="10" onchange="OverlayDiv(this)" FEIFormat="N" FEICheck="N>=3E-10" runat="server" /> mbar
JavaScript
function OverlayDiv(MyInput)
{
alert("te");
var t = true;
if($("#EI_InitialTests_AnalysisPressure").val() == '')
t = false;
alert(t);
}