JSFiddle - React, Tailwind, and code Playground
HTML
<input type="text" id="txtBx" />
JavaScript
document.getElementById("txtBx").value = null;
alert("test 1 textbox is null \n" + (document.getElementById("txtBx").value == null));
alert("test 2 textbox is empty string \n" + (document.getElementById("txtBx").value == ""));