A while ago I answered a question about how to show barcodes on forms in
ServiceNow. I'm just re-posting it here as well as I think it's useful.

So I was able to do this with the help of the
JsBarcode library.

Here's how I did it, and how you can do it too;

1. Create UI Script named jsbarcode and copy/paste the library code
   from: https://cdn.jsdelivr.net/jsbarcode/3.3.20/JsBarcode.all.min.js

2. Create UI Macro with svg with id you will call later.

   <?xml version="1.0" encoding="utf-8" ?>
     <j:jelly trim="false" 
             xmlns:j="jelly:core"
             xmlns:g="glide"
             xmlns:j2="null"
             xmlns:g2="null">
       <svg id="code128"></svg>
       <!--
           <svg id="ean-13"></svg>
           <svg id="ean-8"></svg>
           <svg id="ean-5"></svg>
           <svg id="ean-2"></svg>
           <svg id="upc-a"></svg>
           <svg id="code39"></svg>
           <svg id="itf-14"></svg>
           <svg id="msi"></svg>
           <svg id="pharmacode"></svg>
           -->
     </j:jelly>

3. Create UI Formatter calling UI Macro name plus .xml
   

4. Add UI Formatter to form.
   

5. Add onChange script like so to form;

   function onChange(control, oldValue, newValue, isLoading, isTemplate) {
     /** Run on load and on change.
     if (isLoading || newValue === '') {
       return;
     }
     */
     ScriptLoader.getScripts('jsbarcode.jsdbx', function() {
       console.log('onchange');
       JsBarcode("#code128", newValue);
       /*
       JsBarcode("#ean-13", "1234567890128", {format: "ean13"});
       JsBarcode("#ean-8", "12345670", {format: "ean8"});
       JsBarcode("#ean-5", "12345", {format: "ean5"});
       JsBarcode("#ean-2", "12", {format: "ean2"});
       JsBarcode("#upc-a", "123456789012", {format: "upc"});
       JsBarcode("#code39", "Hello", {format: "code39"});
       JsBarcode("#itf-14", "1234567890123", {format: "itf14"});
       JsBarcode("#msi", "123456", {format: "msi"});
       JsBarcode("#pharmacode", "12345", {format: "pharmacode"});
       */
     });
   }

6. Which should result in something like this;