How do I hide a contact form field until another field is filled?

[chert]

Hello,

I would like a simple script in global.js which follows the logic below but I need your help in writing the script.

If "Name" field =  blank

Hide "Comment" field

Else

Show "Comment" field

Can someone please help me? I provided a screen shot of the form and its HTML.

I understand there are multiple form apps that have conditional logic but I want this to be a learning experience for me. Thank you.

The shopify store is https://permaink.myshopify.com/pages/contact with the store PW = "help".