Jquery 当元素接收到类时，更改另一个元素上的css

我想要完成的事情的简短描述：

当另一个元素获得类时，显示并激活元素上的css动画

稍长一点的描述：

当ID为“widget-1”的li元素获得类“normalopacity”时，我希望DIV“animation-widget-1”中的动画开始

当类“正常不透明度”继续到下一个li元素“widget-2”时。我想隐藏以前的动画（在本例中为DIV“animation-widget-1”），而是显示与当前li元素（在本例中为widget-2）链接的动画

最后：当类“normalopacity”返回到第一个li元素“widget-1”时，我希望动画重新启动

HTML

包含列表和包含隐藏动画的div的部分

<section id="widget-section">
    <div class="function-content">
        <ul class="function-list">
            <li class="normal-opacity" id="widget-1">
                <div>
                    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
                </div>
            </li>
            <li id="widget-2">
                <div>
                    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
                </div>
            </li>
            <li id="widget-3">
                <div>
                    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
                </div>
            </li>
            <li id="widget-4">
                <div>
                    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
                </div>
            </li>
        </ul>
    </div>
    <div class="animations">
        <div class="animated bounceoutdown" id="animation-widget-1">
<i class="material-icons md-48 animated bounceindown">smartphone</i>
<i class="material-icons md-48 animated bounceindown">email</i>
<i class="material-icons md-48 animated bounceindown">chat_bubble_outline</i>
        </div>
    </div>
</section>

CSS

/*MAKES LI ELEMENT HAVE OPACITY 0.5*/

.function-list li {
    opacity: 0.5;
}

.function-list .normal-opacity {
    opacity: 1;
}


/*HIDES THE ANIMATION*/

.animations {
    visibility: hidden;
}


/*DECIDE WHEN ANIMATIONS WILL START*/

#animation-widget-1 {
            animation-delay: 5s;
        }
#animation-widget-1 i:first-child {
            animation-delay: 1s;
        }
#animation-widget-1 i:nth-child(2) {
            animation-delay: 1.3s;
        }
#animation-widget-1 i:last-child {
            animation-delay: 1.6s;
        }

我希望这个问题不要太奇怪，我的描述也不错

GIF列表动画：

---

请评论解决此问题的解决方案/技巧和trix:）

像这样，您只需将一个类链接到li上

.function list li.normal-opacity div{
/*你想激活的代码在这里*/
}

/*MAKES LI ELEMENT HAVE OPACITY 0.5*/

.function-list li {
    opacity: 0.5;
}

.function-list .normal-opacity {
    opacity: 1;
}


/*HIDES THE ANIMATION*/

.animations {
    visibility: hidden;
}


/*DECIDE WHEN ANIMATIONS WILL START*/

#animation-widget-1 {
            animation-delay: 5s;
        }
#animation-widget-1 i:first-child {
            animation-delay: 1s;
        }
#animation-widget-1 i:nth-child(2) {
            animation-delay: 1.3s;
        }
#animation-widget-1 i:last-child {
            animation-delay: 1.6s;
        }