如何在 div 上添加类？

Question

我有一些代码来显示一系列图像。序列完成后（序列的最后一张图片已经出现），我希望将 .d-block 类切换到 div 类 .d-none

可以这样做吗？

onload = function startAnimation() { 
    var frames = document.getElementById("animation").children;
    var frameCount = frames.length;
    var i = 0, j = 0;
    var interval = setInterval(function () {
        frames[i % frameCount].style.display = "none";
        frames[++i % frameCount].style.display = "block";
        j++;
        if(j === 14) {
            clearInterval(interval);
        }
    },100); 
}

#animation img {
    display: none;
}
#animation img:first-child {
    display: block;
}
.d-none{
display:none
}
.d-block{
display:block;
}

<div id="animation"> 
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging01.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging02.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging03.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging04.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging05.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging06.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging07.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging08.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging09.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging10.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging11.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging12.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging13.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging14.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging15.png" />
</div>
<div class="d-none">
    This should appear once the sequence is completed!
</div>

Answer 1

您可以在clearInterval 之后使用document.getElementsByClassName 切换类。检查下面更新的 sn-p...

onload = function startAnimation() { 
    var frames = document.getElementById("animation").children;
    var frameCount = frames.length;
    var i = 0, j = 0;
    var interval = setInterval(function () {
        frames[i % frameCount].style.display = "none";
        frames[++i % frameCount].style.display = "block";
        j++;
        if(j === 14) {
            clearInterval(interval);
            document.getElementsByClassName("d-none")[0].classList.add('d-block');
            document.getElementsByClassName("d-none")[0].classList.remove('d-none');
        }
    },100); 
}

#animation img {
    display: none;
}
#animation img:first-child {
    display: block;
}
.d-none{
display:none
}
.d-block{
display:block;
}

<div id="animation"> 
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging01.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging02.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging03.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging04.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging05.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging06.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging07.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging08.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging09.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging10.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging11.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging12.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging13.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging14.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging15.png" />
</div>
<div class="d-none">
this div is aappear
</div>

Answer 2

你可以改变css：

onload = function startAnimation() { 
    var frames = document.getElementById("animation").children;
    var frameCount = frames.length;
    var i = 0, j = 0;
    var interval = setInterval(function () {
        frames[i % frameCount].style.display = "none";
        frames[++i % frameCount].style.display = "block";
        j++;
        if(j === 14) {
            clearInterval(interval);
            document.getElementsByClassName("d-none")[0].style.display = "block";
        }
    },100); 
}

#animation img {
    display: none;
}
#animation img:first-child {
    display: block;
}
.d-none{
display:none
}
.d-block{
display:block;

<div id="animation"> 
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging01.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging02.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging03.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging04.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging05.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging06.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging07.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging08.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging09.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging10.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging11.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging12.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging13.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging14.png" />
    <img src="http://jumpingfishes.com/dancingpurpleunicorns/charging15.png" />
</div>
<div class="d-none">
    This should appear once the sequence is completed!
</div>

这不需要另一个类