如何使用document.getElementsByClassName

Question

我有两个问题

1. 请帮助我理解一些JavaScript来创建我从W3Schools获得的手风琴菜单

的CSS

    <style>
button.accordion_f {
    background-color: #eee;
    color: #444;
    cursor: pointer;
    padding: 14px;
    width: 100%;
    border: none;
    text-align: left;
    outline: none;
    font-size: 15px;
    transition: 0.4s;
}

button.accordion_f.active, button.accordion_f:hover {
    background-color: #ddd;
    color: blue;
}

button.accordion_f:after {
    content: '\02795';
    font-size: 13px;
    color: #777;
    float: right;       
    margin-left: 5px;  
}

button.accordion_f.active:after {
    color: blue;
    content: "\2796";
}

div.panel {
    padding: 0 14px;
    background-color: white;
    max-height: 0;
    overflow: hidden;
    transition: 0.3s ease-in-out;
    opacity: 0;
}

div.panel.show {
    opacity: 1;
    max-height: 6000px;  
}
</style> 

的JavaScript

<script>
var acc = document.getElementsByClassName("accordion_f");
var i;

for (i = 0; i < acc.length; i++) {
    acc[i].onclick = function(){
    this.classList.toggle("active");
    this.nextElementSibling.classList.toggle("show");       
    }
}
</script>

使用范例

<button class="accordion_f">3rd party compatibility</button>
<div class="panel">
<p>Offers an easy way to connect your Polar training device with 3<sup>rd</sup> party services.</p>
</div>

这正常工作

如果我将其封装在另一个类中（例如，在药丸菜单中），它将无法展开菜单，css似乎可以正常工作，背景阴影等，当我检查元素时看不到脚本，是影响文档的父类。 getElementsByClassName一些如何？

<ul class="tabs">
<button class="accordion_f">3rd party compatibility</button>
<div class="panel">
<p>Offers an easy way to connect your Polar training device with 3<sup>rd</sup> party services.</p>
</div>
</ul>

2. 如何将脚本放入函数并通过onclick或onmouseover调用它？

我试过了：

<button class="accordion_f" onmouseover="accordion_menu()">Activity</button>
<div class="panel">
<p>Tracks your daily activity at five intensity levels for 24 hours a day, seven days a week, and provides a complete picture of all of your activity. It counts your active time, daily burnt calories, steps, distance from steps and sleep.</p>
</div>

function accordion_menu(){
var acc = document.getElementsByClassName("accordion_f");
var i;

for (i = 0; i < acc.length; i++) {
    acc[i].onclick.classList.toggle("active");        
    acc[i].onclick.nextElementSibling.classList.toggle("show");        
 }
} 

这样就打开了所有带有手风琴类的面板，而不仅仅是我想要的活动面板。

Answer 1

它正在运行，IE处于兼容模式，ie8对document.getElementsByClassName的支持不佳