for example :

 A = ['a','b','c']

B =['b']    <--- B is always included in A

my result C == A - B == ['a','c']

Here is my jsfiddle :

http://jsfiddle.net/mlotfi/zhjntqsd/12/

I would like an array that has  this difference :

data-restagencies - data-agencies 

when this button is clicked :

1.  $('button.btn').on('click', function () {

Thanks