How to add the corresponding "variable field name" to the source field name?

Hello! This wasn't my question, but I believe I know what the original poster meant (and have a similar question).

According to Jotform's original example, we need to input something like this into the URL in order to prepopulate the form: fullName[first]=John&fullName[last]=Doe

This is a great and very valuable feature! But it only works if we already know the user's name. Instead, what I think would be more useful is to use variables/custom fields. We see this pretty often in email products like MailChimp or SendGrid; instead of having to send emails one at a time, users will instead use a {name} variable, and the variable will be replaced with each recipient's name. In other words, "Hello {name}" will turn into "Hello Sarah," or "Hello Luis", depending on who the email is sent to.

What I think would be useful (if it doesn't already exist) is to add the same functionality to the pre-population widget. That way, we wouldn't need to create a custom URL for each recipient--and if the recipient ever updates their information (for example, if their last name or email changes), the value of the variable will also update.

We could instead send something like this:
fullName[first]={variable1}&fullName[last]={variable2}

It may be that this functionality already exists and we just haven't located it yet! But any response would be appreciated :)