Custom selector for data in jQuery don't work

I have elements in the DOM that have set data('disabled', true) and I want to create custom selector that will select those elements. I try this:

jQuery.extend(jQuery.expr[':'], { 
    disabled: function(a,i,m) {
        return $(a).data('disabled') === true;
    }
});

and this:

jQuery.expr[':'].disabled = function(a,i,m) {
    return $(a).data('disabled') === true;
};

I also try !!$(a).data('disabled');

but it don't work, $('.parent :disabled') return nothing, even when I have elements that are inside .parent that have data('disabled'). Anybody know why.

It looks like it is because jQuery already has a selector named :disabled, if you rename it it works fine

jQuery(function($){
    jQuery.extend(jQuery.expr[':'], { 
        disabled1: function(a,i,m) {
            console.log('x',arguments)
            return $(a).data('disabled') === true;
        }
    });

    $('.parent :disabled1').hide()
})

Demo: Fiddle