开放式手风琴使用Javascript

问题描述：

https://www.w3schools.com/howto/howto_js_accordion.asp

如何配置手风琴是在一开始打开？

的Javascript：

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

for (i = 0; i < acc.length; i++) { 
    acc[i].onclick = function() { 
    this.classList.toggle("active"); 
    var panel = this.nextElementSibling; 
    if (panel.style.maxHeight){ 
     panel.style.maxHeight = null; 
    } else { 
     panel.style.maxHeight = panel.scrollHeight + "px"; 
    } 
    } 
} 
</script>

后 “为” 你可以运行第一个手风琴的点击事件：'acc [0] .click（）;' – ZiTAL

答

您需要添加.active类.accordion和style="display:block"到子元素p要保持开放

var acc = document.getElementsByClassName("accordion"); 
 
var i; 
 

 
for (i = 0; i < acc.length; i++) { 
 
    acc[i].onclick = function(){ 
 
     this.classList.toggle("active"); 
 
     var panel = this.nextElementSibling; 
 
     if (panel.style.display === "block") { 
 
      panel.style.display = "none"; 
 
     } else { 
 
      panel.style.display = "block"; 
 
     } 
 
    } 
 
}

button.accordion { 
 
    background-color: #eee; 
 
    color: #444; 
 
    cursor: pointer; 
 
    padding: 18px; 
 
    width: 100%; 
 
    border: none; 
 
    text-align: left; 
 
    outline: none; 
 
    font-size: 15px; 
 
    transition: 0.4s; 
 
} 
 

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

 
div.panel { 
 
    padding: 0 18px; 
 
    display: none; 
 
    background-color: white; 
 
}

<h2>Accordion</h2> 
 

 
<button class="accordion active" >Section 1</button> 
 
<div class="panel" style="display:block"> 
 
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> 
 
</div> 
 

 
<button class="accordion">Section 2</button> 
 
<div class="panel"> 
 
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> 
 
</div> 
 

 
<button class="accordion">Section 3</button> 
 
<div class="panel"> 
 
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> 
 
</div>

答

如果我的理解问题，尝试选择第一个（或其他）元素并设置它的显示器，以 “块” 的时候，文件被加载：

acc[0].nextElementSibling.style.display = "block"

d默认代码在这里：https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_accordion –

答

只需添加

ACC [0]。点击（）;

在脚本结束

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

for (i = 0; i < acc.length; i++) { 
    acc[i].onclick = function() { 
    this.classList.toggle("active"); 
    var panel = this.nextElementSibling; 
    if (panel.style.maxHeight){ 
     panel.style.maxHeight = null; 
    } else { 
     panel.style.maxHeight = panel.scrollHeight + "px"; 
    } 
    } 
} 
acc[0].click(); 
</script>

答

您可以使用JavaScript来设置该属性el.nextElementSibling.style.display = 'block'的第一个元素：

document.querySelectorAll('.accordion').forEach(function(el, index) { 
 
    // Add event listener to all elements 
 
    el.addEventListener('click', function() { 
 
    el.classList.toggle('active'); 
 
    el.nextElementSibling.style.display = el.nextElementSibling.style.display === 'block' 
 
     ? 'none' 
 
     : 'block'; 
 
    }); 
 
    
 
    // First element open 
 
    0 === index && (el.nextElementSibling.style.display = 'block'); 
 
});

button.accordion { 
 
    background-color: #eee; 
 
    color: #444; 
 
    cursor: pointer; 
 
    padding: 18px; 
 
    width: 100%; 
 
    border: none; 
 
    text-align: left; 
 
    outline: none; 
 
    font-size: 15px; 
 
    transition: 0.4s; 
 
} 
 

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

 
div.panel { 
 
    padding: 0 18px; 
 
    display: none; 
 
    background-color: white; 
 
}

<h2>Accordion</h2> 
 

 
<button class="accordion active" >Section 1</button> 
 
<div class="panel"> 
 
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> 
 
</div> 
 

 
<button class="accordion">Section 2</button> 
 
<div class="panel"> 
 
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> 
 
</div> 
 

 
<button class="accordion">Section 3</button> 
 
<div class="panel"> 
 
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> 
 
</div>

开放式手风琴使用Javascript

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