You can use jQuery method $.extend() which work in IE 11.
var object = {name: 'John', surname: 'Rowland'};
var newObject = $.extend({}, object);
newObject.age="30";
console.log(object);
console.log(newObject)
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>