我有几行文字，点击后会在下方显示更多文字。我有几个正在使用的Bootstrap图标，并且试图在折叠开关折叠时显示“ +”图标，在打开开关时显示“-”图标。我也在使用Bootstrap进行切换。我在想也许有一套显示：没有另一种可见，但是我似乎不知道该怎么做。预先感谢您的帮助。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css" integrity="sha384-9aIt2nRpC12Uk9gS9baDl411NQApFmC26EwAOH8WgZl5MYYxFfc+NcPb1dKGj7Sk" crossorigin="anonymous">
</head>
<body>
<div class="panel-group" id="accordion">
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a class="accordion-toggle" data-toggle="collapse" href="#collapseOne" id="question1">
<!-- Plus Icon SVG -->
<svg class="bi bi-plus-circle" width="1em" height="1em" viewBox="0 0 16 16" fill="currentColor" xmlns="http://www.w3.org/2000/svg">
<path fill-rule="evenodd" d="M8 3.5a.5.5 0 0 1 .5.5v4a.5.5 0 0 1-.5.5H4a.5.5 0 0 1 0-1h3.5V4a.5.5 0 0 1 .5-.5z"/>
<path fill-rule="evenodd" d="M7.5 8a.5.5 0 0 1 .5-.5h4a.5.5 0 0 1 0 1H8.5V12a.5.5 0 0 1-1 0V8z"/>
<path fill-rule="evenodd" d="M8 15A7 7 0 1 0 8 1a7 7 0 0 0 0 14zm0 1A8 8 0 1 0 8 0a8 8 0 0 0 0 16z"/>
</svg>
<!-- Minus Icon SVG -->
<svg class="bi bi-dash-circle" width="1em" height="1em" viewBox="0 0 16 16" fill="currentColor" xmlns="http://www.w3.org/2000/svg">
<path fill-rule="evenodd" d="M8 15A7 7 0 1 0 8 1a7 7 0 0 0 0 14zm0 1A8 8 0 1 0 8 0a8 8 0 0 0 0 16z"/>
<path fill-rule="evenodd" d="M3.5 8a.5.5 0 0 1 .5-.5h8a.5.5 0 0 1 0 1H4a.5.5 0 0 1-.5-.5z"/>
</svg>
Line of text.
</a>
</h4>
</div>
<div id="collapseOne" class="panel-collapse collapse in">
<div class="panel-body answer">
More text
</div>
</div>
</div>
</div>
<div class="panel-group" id="accordion">
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a class="accordion-toggle" data-toggle="collapse" href="#collapseTwo" id="question2">
<svg class="bi bi-plus-circle" width="1em" height="1em" viewBox="0 0 16 16" fill="currentColor" xmlns="http://www.w3.org/2000/svg">
<path fill-rule="evenodd" d="M8 3.5a.5.5 0 0 1 .5.5v4a.5.5 0 0 1-.5.5H4a.5.5 0 0 1 0-1h3.5V4a.5.5 0 0 1 .5-.5z"/>
<path fill-rule="evenodd" d="M7.5 8a.5.5 0 0 1 .5-.5h4a.5.5 0 0 1 0 1H8.5V12a.5.5 0 0 1-1 0V8z"/>
<path fill-rule="evenodd" d="M8 15A7 7 0 1 0 8 1a7 7 0 0 0 0 14zm0 1A8 8 0 1 0 8 0a8 8 0 0 0 0 16z"/>
</svg>Line of text.
</a>
</h4>
</div>
<div id="collapseTwo" class="panel-collapse collapse in">
<div class="panel-body answer">
More text
</div>
</div>
</div>
</div>
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js" integrity="sha384-OgVRvuATP1z7JjHLkuOU7Xw704+h835Lr+6QL9UvYjZE3Ipu6Tp75j7Bh/kR0JKI" crossorigin="anonymous"></script>
</body>
</html>您可以添加一个事件侦听器并使用属性来产生这种效果
plus= document.getElementsByClassName('bi-plus-circle')[0]
minus= document.getElementsByClassName('bi-dash-circle')[0]
plus.addEventListener('click',()=>{
plus.setAttribute('display','none')
minus.setAttribute('display','')
})
minus.addEventListener('click',()=>{
plus.setAttribute('display','')
minus.setAttribute('display','none')
toggle=true
})