update custom field user profile from front end form

Question

I've created a custom field called "istituto" in the user profile section that works properly if it is updated within the profile itself.

I have created a custom registration form with a field called "istituto". The submit button of this form is a div with class ".form_acc_2" and the field "instituto" has an id #dhvc_form_control_istituto. I wrote in jquery a code that fetches the value when inserted:

var istituto = '';
jQuery('div.form_acc_2').click(function(){   
   var istituto = jQuery('input#dhvc_form_control_istituto').val();
   if(istituto.length != 0)
   alert(istituto);
   return istituto;   
   })

Now the value is in the variable "instituto". How can I update the custom field "istituto" inside the user profile using the update_user_meta function?

Did I use a wrong approach?

Answer 1

ok everything fixed at the time, I modified the oroginal form with "register_form" and then I called the input with that value in my custom form.