You can use the free Toolbox plugin’s run javascript action and also the Javascript to Bubble element. Here is a few screenshots of how you would set it up. In my example I am using a function “btoa” because I am encoding a string to base64 but if you are decoding then you will use “atob”.
Here is the Javascript to Bubble element. You just need to give it a suffix.

Here is the run javascript action you just need to change the btoa to atob and pass in your encoded base64 string. Then on the bottom it should be bubble_fn_yourSuffix(encodedString)

Then you can use the value by referencing the element and its value

2 Likes