How to limit the number of keywords in Bridge

Great job as always SuperMerlin!

I extended your script with a very simple interactive prompt. There is no error checking or safeguards to ensure that only digits are entered, however that should not be too hard to add if required.

//Limit Keywords with Prompt.jsx
//How to limit the number of keywords in Bridge
//community.adobe.com/t5/bridge/how-to-limit-the-number-of-keywords-in-bridge/m-p/10945147

#target bridge
if (BridgeTalk.appName == "bridge") {
   keyLimit = MenuElement.create("command", "Limit Keywords", "at the end of tools");
}
keyLimit.onSelect = function () {
   // Interactive Step
   NumberOfKeywords = Window.prompt("Please enter the keyword length limit:", "5");
   try {
      if (ExternalObject.AdobeXMPScript == undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript");
      var sels = app.document.selections;
      for (var a = 0; a < sels.length; a++) {
         var thumb = new Thumbnail(sels[a]);
         var md = thumb.synchronousMetadata;
         var xmp = new XMPMeta(md.serialize());
         if (!xmp.doesPropertyExist(XMPConst.NS_DC, "subject")) continue;
         var keys = [];
         keys = getArrayItems(XMPConst.NS_DC, "subject");

         function getArrayItems(ns, prop) {
            var arrItem = [];
            var items = xmp.countArrayItems(ns, prop);
            for (var i = 1; i <= items; i++) {
               arrItem.push(xmp.getArrayItem(ns, prop, i));
            }
            return arrItem;
         };
         if (keys.length > NumberOfKeywords) {
            xmp.deleteProperty(XMPConst.NS_DC, 'subject');
            for (var k = 0; k < NumberOfKeywords; k++) {
               xmp.appendArrayItem(XMPConst.NS_DC, 'subject', keys[k], 0, XMPConst.PROP_IS_ARRAY);
            }
         }
         var updatedPacket = xmp.serialize(XMPConst.SERIALIZE_USE_COMPACT_FORMAT);
         thumb.metadata = new Metadata(updatedPacket);
      }
   } catch (e) {
      alert(e + "\n" + e.line);
   }
};

https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html

Entering the keywords in the following order, with a mixutre of digits and alphabetical characters:

1, 2, 3, 4, 5, six, 7, eight

Has the following display in Bridge CC2019:

So as Lumigraphics notes, even within Adobe software, the display order is not consistent.

At least the raw data of file info matches what ExifTool states, which is the order of input/entry:

[IPTC] Keywords : 1, 2, 3, 4, 5, six, 7, eight 
[XMP-dc] Subject : 1, 2, 3, 4, 5, six, 7, eight

So a solution using ExifTool is readily available, if you are willing to use a CLI based program (there are GUI front ends that can be used to hide most of the command line use of ExifTool if one does need a crutch).

Just uncheck the ones you don't want to use.