How to get a lock on iframe.

Question

I want my website visitors to see the content in the iframe after filling a form. Hence I want to lock iframe so no one can see the content before filling the form. Is there any way by which a user may only see the content after filling the form. If yes, how to do it? How to make/modify such form and iframe tag?

Please help me ...

Answer 1

//use javascript

form.onsubmit = iframe.src = "https://dummy.file"