var original = "test1,test2,test3"

var updated = "test1,test2,test4,test5"

var originalArray  = original.split(',');

var updatedArray  = updated.split(',');

console.log(originalArray.length)
console.log(updatedArray.length)

console.log($(originalArray).not(updatedArray))
console.log($(updatedArray).not(originalArray))

["test4", "test5", prevObject: jQuery.fn.jQuery.init[4], context: undefined, selector: ".not(test1,test2,test3)", constructor: function, init: function…]