JS

Question

当我向上滚动页面时，我试图找出为什么element2不会缩减到300像素。当我向下滚动它增长但当我向上滚动时它不会收缩。我也很好奇为什么有时当我在滚动区域时（例如延迟反应），宽度会自动切换。

$(document).ready( function(){
        var lastSCroll =  0;
        $(window).on("scroll", function(){
            var scrolled = $(window).scrollTop();
            if(scrolled  > 470 && scrolled <1150){
                $(".element2").show("slow").css({"top" : scrolled + 30});
            }
            if( scrolled > 770 && scrolled < 1150 && scrolled > lastSCroll){
                $(".element2").animate({"width" : "500px"})
            }   
            if(scrolled > 770 && scrolled < 1150 && scrolled < lastSCroll){
                    $(".element2").animate({"width" : "300px"})
                }
                $(".display").html(scrolled + ": lastScroll--> " + lastSCroll)

            lastSCroll = scrolled ;
  });

HTML：

<body>
<div class="element">Test</div>
<div class="element2">TEST 2</div>
<div class="display"></div>
<div class="firstCont"></div>
<div class="secondCont"></div>
<div class="thirdCont"></div>
<div class="fourthCont">4th</div>

CSS：

    *{
        margin: 0;
        padding: 0;
    }
    .firstCont{
        height: 100vh;
        background: pink;
    }
    .display{
        position: fixed;
        top: 0;
        right: 0;
        padding: .5em 1em;
        background: rgba(120,0,0,0.3);
        z-index: 5;
    }
    .secondCont{
        height: 100vh;
        background: hotpink;
    }
    .thirdCont{
        height: 100vh;
        background: seagreen;
    }
    .fourthCont{
        height: 100vh;
        background: skyblue;
    }
    .element{
        position: absolute;
        width: 300px;
        background: blue;
        height: 200px;
        display: none;
    }
    .element2{
        background: gold;
        width: 300px;
        height: 200px;
        position: absolute;
        display: none;
    }

Answer 1

在stop()之前添加animate()似乎可以解决问题。它可以防止动画队列建立并导致奇怪的行为。 https://jsfiddle.net/o9o7ogsz/2/

JS

$(document).ready(function () {
    var lastSCroll = 0;
    $(window).on("scroll", function () {
        var scrolled = $(window).scrollTop();
        if (scrolled > 470 && scrolled < 1150) {
            $(".element2").show("slow").css({
                "top": scrolled + 30
            });
        }
        if (scrolled > 770 && scrolled < 1150 && scrolled > lastSCroll) {
            $(".element2").stop().animate({
                "width": "500px"
            })
        }
        if (scrolled > 770 && scrolled < 1150 && scrolled < lastSCroll) {
            $(".element2").stop().animate({
                "width": "300px"
            })
        }
        $(".display").html(scrolled + ": lastScroll--> " + lastSCroll)

        lastSCroll = scrolled;
    });
});

在向上滚动页面时尝试为div设置动画

1 个答案:

JS