JSFiddle - React, Tailwind, and code Playground

HTML

<div id="null"></div>
<div id="empty"></div>
<div id="notempty"></div>

JavaScript

var nul = null;
var empty = "";
var notempty = "string";

function test(id) {
    if (!id || id === '') {
        return "is null or empty"
    }
    return "is a string with at least 1 char"
}
            
$('#null').html(test(nul))
$('#empty').html(test(empty))
$('#notempty').html(test(notempty ))