JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>TEST</title>
</head>
<body>
    
<form id="DoesTheRealFormHaveAnId">

<table width="100%">
    <tbody>
        <tr>        
            <td align="left" width="150">Destination: </td>
            <td><input id="dest" name="dest" value="" size="5" type="text"></td>
        </tr>
        <tr>        
            <td align="left" width="150">Priority: </td>
            <td><input id="prio" name="prio" type="text" value="285"></td>
        </tr>
        <tr>        
            <td align="left" width="150">Success: </td>
            <td><input id="succ" name="succ" type="text" value="6"></td>
        <tr>
            <td align="center" colspan="2">
                <input type="submit" value="Submit">
            </td>
        </tr>        
    </tbody>
</table>        

<br/>

<table border="0" cellspacing="0" width="100%">
    <tbody>
        <tr>
            <td class="user">
            &nbsp;
            <a href="#" class="nav" title="Logout John">Logout</a>

            &nbsp;(User: Steve)

            </td>
        </tr>
    </tbody>
</table>

</form>    
    
</body>
</html>

CSS

body {margin-top:20px;}
table {background-color:#ccc;padding:20px 10px;}

JavaScript

//--- Make sure this list of names is all uppercase.
var usersWhoCanSetPriority  = ['JOHN', 'LUKE', 'JEFF', 'MAX', 'ANDY'];
var excludedDestinations    = ['12', '22'];

var bDisablePrio    = true;
var tdNodes         = document.getElementsByTagName ("TD");
for (var J = tdNodes.length - 1;  J >= 0;  --J) {
    var tdNode      = tdNodes[J];
    if (tdNode.className == "user") {
        var userName        = tdNode.textContent.replace (
            /^(?:.|\n|\r)+\(User:\s+([^)]+)\)(?:.|\n|\r)+$/i, "$1"
        ).toUpperCase ();
        if (usersWhoCanSetPriority.indexOf (userName) > -1) {
            bDisablePrio = false;
        }
    }
}

if (bDisablePrio) {
    var oldInput    = document.getElementsByName ("prio");
    if (oldInput  &&  oldInput.length) {
        oldInput[0].setAttribute ("disabled", "disabled");
    }

    var destInput   = document.getElementsByName ("dest");
    if (destInput  &&  destInput.length) {
        destInput[0].addEventListener (
            "change",
            function (zEvent) {
                bCheckdestinationValue (destInput[0]);
            },
            false
        );

        //--- Extra added to try and get FF2 to behave as later versions do.
        destInput[0].addEventListener (
            "keydown",
            function (zEvent) {
                if (zEvent.keyCode == 13) {
                    if ( bCheckdestinationValue (destInput[0]) ) {
                        console.log ("Enter blocked.");
                        zEvent.preventDefault ();
                        zEvent.stopPropagation ();
                        return false;
                    }
                }
            },
            true
        );

        destInput[0].form.addEventListener (
            "submit",
            function (zEvent) {
                var destValue   = destInput[0].value;
                if (    destValue === ''
                        ||  excludedDestinations.indexOf (destInput[0].value) > -1
                ) {
          ...