Stop body from scrolling with Foundation 5 Reveal-Modal

Hide-Foundation-Modal-BG-Scroll.js

$(".reveal-modal").on("open", function () {
    $("body").addClass("modal-open");
});
$('.close-reveal-modal').bind("click touchstart", function () {
    $('body').removeClass('modal-open');
});

Styles.css

body.modal-open {
   overflow: hidden;
   position: fixed;
}
.reveal-modal {
   overflow-y: auto;
   height: 100%;
   position: fixed;
}

FYI, the open event binding is going to be depreciated in ver 5.4
Best to use the namedspaced events open.fndtn.reveal, opened.fndtn.reveal, close.fndtn.reveal and closed.fndtn.reveal

$('.reveal-modal').on('open.fndtn.reveal', '[data-reveal]', function () {
    $('body').addClass('modal-open');
});
$('.reveal-modal').on('close.fndtn.reveal', '[data-reveal]', function () {
    $('body').removeClass('modal-open');
});