js点击箭头旋转的实现

我们经常可以在网页中看到向下的箭头，并且在我们点击时，箭头会发生旋转，这又是如何做到的呢？我们来看一看，先上效果图：

可以看到，在点击箭头时，箭头的方向旋转了，并且再次点击回到原来的样子，我们看一看代码：

首先是html样式

    

        
            
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 html代码没什么特别的，然后我们来看css代码：

body {
    background-color: #F2F2F2;
}


.nav {
    height: 48px;
    width: 1536px;
    margin: 0 auto;
    background-color: #006FC9;
    display: flex;
}


button {
    width: 48px;
    height: 48px;
    background-color: #006FC9;
    cursor: pointer;
    border: none;
}

button i {
    color: white;
}

button:hover {
    background-color: #006BC3;
}




.user {
    height: 48px;
    width: 130px;
    display: inline-block;
    text-align: center;
}


.user>a {
    color: white;
    line-height: 48px;
    font-weight: 600;
}

.user:hover {
    background-color: #006BC3;
}

.wrapper-1 {
    display: inline-flex;
    height: 100%;
    align-items: center;
    margin-left: 0px;
    color: white;
}



.middle-nav {
    height: 48px;
}

.middle-nav>ul>li {
    float: left;
    margin-left: 20px;
    height: 48px;
}

.middle-nav>ul>li>a {
    color: white;
    line-height: 48px;
    font-size: 14px;
    padding: 10px;
}

.middle-nav>ul>li:hover {
    background-color: #006BC3;
}

i {
    padding-left: 3px;
}


.dropdown-item {
    position: relative;
}

.dropdown-content {
    position: absolute;
    z-index: 10;
    width: 180px;
    height: 140px;
    background-color: white;
    box-shadow: 1px 1px 5px #D4D4D4;
}

.dropdown-content>ul>li {
    width: 180px;
    height: 35px;
}

.dropdown-content>ul>li>a {
    line-height: 35px;
    color: #201F1E;
    padding-left: 6px;
    font-size: 14px;
}

.dropdown-content li:hover {
    background-color: #F4F4F4;
}

.arrow {
    margin-left: 3px;
    transform: rotate(180deg);
    transition: all 0.5s;

}

.box-style {
    animation: move 0.1s 1 linear;
}

@keyframes move {
    from {
        height: 0;
    }

    to {
        height: 140px;
    }
}


.right-nav {
    margin-left: 700px;
}

.right-nav>a {
    display: inline-block;
    height: 48px;
    width: 48px;
    text-align: center;
}

.right-nav i {
    color: white;
    line-height: 48px;

}

.right-nav>a:hover {
    background-color: #006BC3;
}

最后是js代码：

// 导航栏下拉样式
let content = document.getElementsByClassName("dropdown-content")[0];
let dropitem = document.getElementsByClassName("dropitem")[0];
let icon = document.getElementsByClassName("icon")[0]
function appearBox(e) {
    console.log(content);
    if (content.style.display == "none") {
        content.style.display = "block"
        
    } else {
        content.style.display = "none" 
    }
    if(icon.classList.contains("arrow")){
        icon.classList.remove("arrow");
    }else{
        icon.classList.add("arrow");
    }
    
    content.classList.add("box-style");
}

好了，今天就到这里了，喜欢就关注我吧~~~~