swiper组件实现向上翻页时缩小

var mySwiper = new Swiper ('.swiper-container', {
    direction: 'vertical',
    loop: true,
    // 如果需要前进后退按钮
    nextButton: '.swiper-button-next',
    prevButton: '.swiper-button-prev',
    effect : 'coverflow',
    //slidesPerView: 3,
    centeredSlides: true,
    stretch:500,
    coverflow: {
        rotate: 30,
        stretch: 10,
        depth: 60,
        modifier: 4,
        slideShadows : false
    }
})