Select the correct input when using input group after pressing a button
If the input group perhaps contains additional input elements this won't work. I think that you should bind the button to the input field by declaring a new attribute to the button which is connected to the input's id. Like so:

&lt;button type="button" class="btn btn-default increase" data-bind="rooms"&gt;&lt;span class="glyphicon glyphicon-plus"&gt;&lt;/span&gt;&lt;/button&gt;


It now contains the input ID which this button is connected to. Now in your JavaScript try something like this:

$(".increase").click(function() {
  var input = $('#' + $(this).data('bind'));
  input.val(input.val++);
});


It will use the data-bind attribute to connect to the specific input element and increase this value by 1 (++).