W3手风琴-默认打开/页面加载

Question

我正在遵循W3手风琴指南。 我想知道如何修改代码，以便默认情况下或在页面加载时将其打开。

以下是其实用的操作方法示例的链接：

https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_accordion_symbol

谢谢

Answer 1

编辑脚本成为：

这将启动面板，使其最初具有maxHeight，直到之后等待。

 var acc = document.getElementsByClassName("accordion"); var i; for (i = 0; i < acc.length; i++) { var panel = acc[i].nextElementSibling; panel.style.maxHeight = panel.scrollHeight + "px"; 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"; } } } 

 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; } button.accordion:after { content: '\\002B'; color: #777; font-weight: bold; float: right; margin-left: 5px; } button.accordion.active:after { content: "\\2212"; } div.panel { padding: 0 18px; background-color: white; max-height: 0; overflow: hidden; transition: max-height 0.2s ease-out; } 

 <h2>Accordion with symbols</h2> <p>In this example we have added a "plus" sign to each button. When the user clicks on the button, the "plus" sign is replaced with a "minus" sign.</p> <button class="accordion">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> 

如果您不喜欢它，则可以在加载时使用jQuery单击全部。

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

 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; } button.accordion:after { content: '\\002B'; color: #777; font-weight: bold; float: right; margin-left: 5px; } button.accordion.active:after { content: "\\2212"; } div.panel { padding: 0 18px; background-color: white; max-height: 0; overflow: hidden; transition: max-height 0.2s ease-out; } 

 <h2>Accordion with symbols</h2> <p>In this example we have added a "plus" sign to each button. When the user clicks on the button, the "plus" sign is replaced with a "minus" sign.</p> <button class="accordion">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> 

代码的第二行仅单击所有它们。 （@Michael Coker，谢谢您的提醒！以为是jQuery函数。）

Answer 2

在要打开的索引上触发.click() 。 acc[0].click()将打开第一个。

 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(); 

 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; } button.accordion:after { content: '\\002B'; color: #777; font-weight: bold; float: right; margin-left: 5px; } button.accordion.active:after { content: "\\2212"; } div.panel { padding: 0 18px; background-color: white; max-height: 0; overflow: hidden; transition: max-height 0.2s ease-out; } 

 <h2>Accordion with symbols</h2> <p>In this example we have added a "plus" sign to each button. When the user clicks on the button, the "plus" sign is replaced with a "minus" sign.</p> <button class="accordion">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>