buttonName change doesnt work

[HiteshVaghela]

I want to change the button contextual class but its not working
I tried
$(":file").filestyle({buttonName: "btn-primary"});
as well as
<input type="file" class="filestyle" data-buttonName="btn-primary">
FYI: I am using dynamic file input.

[HiteshVaghela]

Got the solution was using
$(":file").filestyle();
$(":file").filestyle({buttonName: "btn-primary"});

So last statement wasn't getting affected.
Silly mistake