当元素底部向上滚动到视图中时使航点触发

Question

如果我想在元素滚动up 进入视野时立即触发航路点怎么办？当您向下滚动时，我有一个航点发生。这很好用。但我希望元素滚动回视图（屏幕底部的元素顶部）后立即触发另一个航路点。

$(".picture").waypoint(function(direction){
            var $this = $(this);
            if (direction === "down") {
                setTimeout(function()
                    {
                        $this.children('.cutline_background').animate({"left":"0px"},2500, function(){});
                        $this.children('.text').animate({"left":"40px"},2500, function(){});
                    }, 3000);

            } 
    }, {offset: 0 });
    $(".picture").waypoint(function(direction){
            var $this = $(this);
            if (direction === "up") {
                $this.children('.cutline_background').css("left", "-20%");  
                $this.children('.text').css("left", "-20%");

            } 
    }, {offset: '90%' }); //this doesn't seem to be working

Answer 1

Waypoints 有一个偏移别名：bottom-in-view

$('.thing').waypoint(function(direction) {
  // do things
}, {
  offset: 'bottom-in-view'
})