How to disable an input field, based on the displayed user text?

Question

I have this code snippet that works:

var oldInput = document.getElementsByName ("prio");
oldInput[0].setAttribute ("disabled", "disabled");

And this is the relevant, target-page HTML (corrected):

<div id="content">
    <p>(CONTENT)</p>
    <form>
      <p>Priority: <input name="prio" type="text" value="285"></p>
      <p>Success: <input name="succ" type="text" value="6"></p>
    </form>
</div>
<table border="0" cellspacing="0" width="100%">
    <tbody>
        <tr>
            <td class="user">
            &nbsp;
            <a href="#" class="nav" title="Logout John">Logout</a>

            &nbsp;(User: John)
            </td>
        </tr>
    </tbody>
</table>

See it at jsfiddle.net/Kc3BB/3.

I have 1 access-point for many users. but I want 5 users to be able to change the prio value. You can see that the username is in the footer.

Is it possible to do that in javascript with the code above for Firefox 2.x and without jQuery?

Example:

if USER (from footer) == JOHN || LUKE || JEFF || MAX || ANDY
do nothing

else
disable PRIO BOX (from content)

Answer 1

This should work in Firefox 2.0:

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

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");
    oldInput[0].setAttribute ("disabled", "disabled");
}

See the updated Fiddle.