I think, if you will access through element name or class (if it is unique), then you can get the id.
// Only when the name is unique for this element
var inputs = document.getElementsByName("DateLead_DateEnd");
alert(inputs[0].id);
OR
// Only when class name is unique for this element
var inputs = document.getElementsByClassName("k-input");
alert(inputs[0].id);
Hope, this will help you.