javascript - 选择下拉菜单后如何更改img内容

Question

选择下拉列表后，我想更改图像的内容。但是在选择了活跃的伪类之后，它一直在闪烁。到目前为止，我已经尝试了许多伪类，但没有一个起作用。谁能告诉我我做错了什么？

var expanded = false;
function showCheckboxes() {
    var checkboxes = document.getElementById("checkboxes");
    if (!expanded) {
        checkboxes.style.display = "block";
        expanded = true;
    } else {
        checkboxes.style.display = "none";
        expanded = false;
    }
}

这里是直播

var expanded = false;

function showCheckboxes() {
  var checkboxes = document.getElementById("checkboxes");
  if (!expanded) {
    checkboxes.style.display = "block";
    expanded = true;
  } else {
    checkboxes.style.display = "none";
    expanded = false;
  }
}

.multiselect {
  width: 100px;
}

.selectBox {
  position: relative;
}

.selectBox select {
  width: 100%;
  font-weight: bold;
}

.overSelect {
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
}

#checkboxes {
  display: none;
  border: 1px gray solid;
}

#checkboxes label {
  display: block;
}

#checkboxes label:hover {
  background-color: yellow;
}

select {
  -webkit-appearance: none;
  -moz-appearance: none;
  text-indent: 1px;
  text-overflow: '';
  background-color: transparent;
  width: 100px !important;
}

.select-container {
  display: flex;
  width: 100px;
  background-color: gray;
}

.drop-arrow {
  content: url("https://cdn3.iconfinder.com/data/icons/fatcow/32/cursor.png");
}

.selectBox:active .drop-arrow {
  content: url("https://cdn0.iconfinder.com/data/icons/fatcow/32/change_password.png");
}

<div class="multiselect">
  <div class="selectBox" onclick="showCheckboxes()">
    <div class="select-container">
      <select>
        <option>Select an option</option>
      </select>
      <img class="drop-arrow" alt="">
    </div>

    <div class="overSelect"></div>
  </div>
  <div id="checkboxes">
    <label for="one"><input type="checkbox" id="one">First checkbox</label>
    <label for="two"><input type="checkbox" id="two">Second checkbox</label>
    <label for="three"><input type="checkbox" id="three">Three checkbox</label>
  </div>
</div>

标签： javascriptcss

Answer 1

朋友，问题出在 selectBox:active .drop-arrow 它仅在按下 clic 时才有效，您可以像下面的代码一样进行操作；我看到的另一个问题是，在这种情况下，您必须将 flex-grow、flex-shrink、flex-basis 添加到 flex 容器的子项 .select-container，此代码可以使用 jquery toogleclass() 检查它

var expanded = false;
function showCheckboxes() {
	var checkboxes = document.getElementById("checkboxes");
	if (!expanded) {
		checkboxes.style.display = "block";
    $(".select-container div").removeClass("drop-arrow");
    $(".select-container div").addClass("drop-arrow2");
		expanded = true;
	} else {
    $(".select-container div").removeClass("drop-arrow2");
    $(".select-container div").addClass("drop-arrow");
		checkboxes.style.display = "none";
		expanded = false;
	}
}

.multiselect {
	width: 140px;
}

.selectBox {
	position: relative;
}

.selectBox select {
	width: 100%;
	font-weight: bold;
}

.overSelect {
	position: absolute;
	top: 0;
	left: 0;
	bottom: 0;
	right: 0;
}

#checkboxes {
	display: none;
	border: 1px gray solid;
}

#checkboxes label {
	display: block;
}

#checkboxes label:hover {
	background-color: yellow;
}

select {
	-webkit-appearance: none;
	-moz-appearance: none;
	text-indent: 1px;
	text-overflow: '';
	background-color: transparent;
	flex:1 0 auto;
}
.select-container {
	display: flex;
	background-color: gray;
  width:auto; 
}


.drop-arrow {
flex:1 0 auto;
display:block;
width: 50px;
height: 35px;
background-image:url("https://cdn3.iconfinder.com/data/icons/fatcow/32/cursor.png");
background-repeat: no-repeat;
   
}

.drop-arrow2 {
	content: url("https://cdn0.iconfinder.com/data/icons/fatcow/32/change_password.png");
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="multiselect">
				<div class="selectBox" onclick="showCheckboxes()">
					<div class="select-container">
						<select>
							<option>Select an option</option>
						</select>
            <div class="drop-arrow" alt=""></div>
					</div>
					
					<div class="overSelect"></div>
				</div>
				<div id="checkboxes">
					<label for="one"><input type="checkbox" id="one">First checkbox</label>
					<label for="two"><input type="checkbox" id="two">Second checkbox</label>
					<label for="three"><input type="checkbox" id="three">Three checkbox</label>
				</div>
			</div>

检查我的笔https://codepen.io/Qleoz12/pen/QzPQvp