javascript - 如何编辑 jQuery 动画以显示在元素中间？

Question

I am using this code from JS Fiddle to create a fade animation with elements on a web page.现在，一旦整个元素在窗口中可见，该元素就会淡入。有什么方法可以编辑它以便我可以更快地触发淡入淡出动画吗？理想情况下，当只有一半元素而不是整个元素可见时，将触发淡入淡出动画。

这是触发此动画的 JavaScript:

/* every time the window is scrolled ... */
 $(window).scroll( function(){
    /* check the location of each desired element */
    $('.fade-in').each( function(i){
        var bottom_of_object = $(this).offset().top + $(this).outerHeight();
        var bottom_of_window = $(window).scrollTop() + $(window).height();
        /* if the object is completely visible in the window, fade it in */
        if( bottom_of_window > bottom_of_object ){
            $(this).animate({'opacity':'1'},600);
        }
    });
});
});

Answer 1

将 bottom_of_object 值更改为小于原始高度的值

var bottom_of_object = $(this).offset().top + $(this).outerHeight() / 3; //we dived by 3 here at the end.