How to pass title to simpleForm2 field?

Question

Joomla

I edit the site on joomla 2.5. There is a catalog of goods through K2, and in the product card there is a simpleForm2 form, which is displayed through fancybox1.2. I set in the form a field with the name of the product, which it should receive when loading the page from the page id. But here's the problem: if the field is outside the form, it gets the value, if the field is in the form, it is empty when it is opened. The form is written in moduleposition. Please help. Thank you)
I pass the value like this:

<input type="text" value="" name="total" id="total">
 
var obj=document.getElementById("total");
obj.value="твои данные";