Question

 var regfbnaam = $('#regfbnaam');
 $('#regnaam').focusin({param1: regfbnaam},removeClass);

function removeClass(e)
{
    param1.removeClass('hidden');
}

Error in console.log: param1 is nog defined. Means he doesn’t get the value of my param1. What am i doing wrong here?

(trying to get a variable with a onclick event to my function)

Answer 1

Try this (tested)

function removeClass(e) {  
    var param1 = e.data.param1;
    param1.removeClass('hidden');
}
jQuery(document).ready(function($) {
    var regfbnaam = $('#regfbnaam');
    $('#regnaam').focusin({param1: regfbnaam},removeClass); 
});

Reference:

event.data

.focusin()