Transfer form data from a form to an external form

I am trying to find a way that I can have a user fill out a small form o开发者_如何学Pythonn my site and then on submit link to an external form (that I have no control over) and populate the information that has already been entered.

Is this even possible? my initial though is using Javascript to append the information to the url but then how would i retrieve it? Maybe using an iframe?

any help would be appreciated!

EDIT: I wanted to clarify. i would like tthe fields of the external form to autopoulate the information they entered on my site so that the visitor could enter the other info that I dont need. Can I do that with cURL?

It's possible in JavaScript. If you know what the output will be in 'external submit' you can filter it and print this out on your site. Than it's ajax related.

Another way is curl, with PHP. With some Regular expression you can filter out the information you need on your own site.