Auto-Format Phone Number will typing on forms

Hi all,

Does anyone have experience using Javascript to auto-format a phone number while someone types it? I know you can use "mask input" to request a specific format, but I'm more interested in having Javascript do this for the user automatically as they type. I find this to be a pretty slick user experience.

I found this article in Stack Overflow: https://stackoverflow.com/questions/65240236/autoformat-input-field

I'm not sure if this is possible using Marketo forms or not. Would love any input from any coders out there!

Thanks,

Ben