Q: how to pass an element to a function I would like to pass the form.find element to my function AvailabilityChecker. I tried to get the elements Attribute with no success. Whats wrong?
var AvailabilityChecker = function (ev, el) {   
       console.log("arguments: ",Array.prototype.slice.call(arguments)); //gives: arguments:  Array [ Object ]
       console.log(ev);
       console.log("AvailabilityChecker: ",el.attr('AvailabilityChecker') //gives Typeerror
}


form.find("input[AvailabilityChecker]").keyup(AvailabilityChecker.bind(this));


A: The el is not going to be an attribute magically appended as an argument. So you need to do it another way. And using .bind() is also changes how you can get the element reference


var AvailabilityChecker = function (ev) {  
  console.log("1-DOM", ev.target.getAttribute("AvailabilityChecker"))
  console.log("1-JQ",$(ev.target).attr("AvailabilityChecker"))
}

$("input[AvailabilityChecker]").keyup(AvailabilityChecker.bind(this));

var AvailabilityChecker2 = function (ev) {  
  console.log("2-DOM", this.getAttribute("AvailabilityChecker"))
  console.log("2-JQ",$(this).attr("AvailabilityChecker"))
}

$("input[AvailabilityChecker]").keyup(AvailabilityChecker2);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input AvailabilityChecker="aaaa">


