Combining jquery functions – on() hover/mouseenter/mouseleave

You can bind to both together and check the event.type:

$(document).on('mouseenter mouseleave', '.my-elements', function (ev) {
    mouse_is_inside = ev.type === 'mouseenter';
});

Or, if you want to keep them separate, .on has another syntax that takes an event map:

$(document).on({
    mouseenter: function () {
        mouse_is_inside = true;
    },

    mouseleave: function () {
        mouse_is_inside = false;
    }
}, '.my-elements');