SelectBoxIt插件与自定义CSS样式冲突问题求助

我帮你分析下问题的根源：你的自定义CSS中给#containerSelect设置了display: flex和flex-flow: row wrap，而SelectBoxIt插件动态生成的下拉选项容器会继承这个flex布局属性，导致原本应该垂直排列的选项变成了水平排列，空间不足时就出现了折叠的情况。

解决方案 #

你只需要添加一段CSS，强制覆盖插件下拉选项容器的flex布局属性，让它恢复默认的垂直排列：

/* 修复SelectBoxIt下拉选项的布局冲突 */
.selectboxit-container .selectboxit-options {
  display: block !important;
  flex-flow: initial !important;
  flex-direction: column !important;
}

修改后的完整代码 #

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/jquery.selectboxit/3.8.0/jquery.selectBoxIt.css" />
<style>
body{
background: linear-gradient(0deg, rgba(100,100,100,1) 0%, rgba(165,165,165,1) 46%, rgba(186,186,190,1) 49%, rgba(205,205,208,1) 50%, rgba(222,218,218,1) 58%, rgba(221,221,221,1) 91%, rgba(181,182,182,1) 100%);
height: 1080px;
}
nav{
background-color: turquoise;
}
ul{
list-style-type: none;
display: flex;
justify-content: space-between;
align-items: center;
width: 70%;
margin: auto;
padding-top:5%;
}
#containerInput{
display: flex;
flex-flow: row wrap;
justify-content: space-between;
width: 40%;
margin: auto;
margin-top:10%;
}
input{
border: none;
height: 160px;
width: 220px;
background-color: #0e3d73;
color: white;
font-size:2em;
text-align: center;
}
#arrow{
margin-top:9%;
}
#arrow img{
height:50px;
width:50px;
}
#containerSelect{
display: flex;
justify-content: space-between;
flex-flow: row wrap;
width: 40%;
margin: auto;
margin-top:2%;
}
select{
width: 220px;
height: 40px;
}
/* 新增的修复样式 */
.selectboxit-container .selectboxit-options {
  display: block !important;
  flex-flow: initial !important;
  flex-direction: column !important;
}
</style>
</head>
<body onload="convertDineroBottom()">
<div id="containerSelect">
<select id="from" onchange="convertDineroBottom()" >
<option value="EUR" data-iconurl="https://upload.wikimedia.org/wikipedia/commons/b/b7/Flag_of_Europe.svg">EUR</option>
<option value="USD" data-iconurl="https://cdn.countryflags.com/thumbs/united-states-of-america/flag-400.png">USD</option>
<option value="GBP" data-iconurl="https://cmkt-image-prd.global.ssl.fastly.net/0.1.0/ps/221487/910/607/m1/fpnw/wm0/united-kingdom-flag-1-.jpg?1414512427&s=f16b2cb24fd704ffcf14b18ee18b5f4e">GBP</option>
<option value="JPY">JPY</option>
<option value="HKD">HKD</option>
</select>
<select id="to" onchange="convertDineroTop()">
<option value="GBP">GBP</option>
<option value="EUR">EUR</option>
<option value="USD">USD</option>
<option value="JPY" selected>JPY</option>
<option value="HKD">HKD</option>
</select>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.0/jquery-ui.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery.selectboxit/3.8.0/jquery.selectBoxIt.min.js"></script>
<script>
function convertDineroBottom() {
var fromCurrency = document.getElementById("from").value;
var toCurrency = document.getElementById("to").value;
fetch("https://api.exchangeratesapi.io/latest?base=" + fromCurrency)
.then((resp) => resp.json())
.then(function(data){
(fromCurrency===toCurrency) ? document.getElementById("toQuantity").value = document.getElementById("fromQuantity").value : document.getElementById("toQuantity").value = data.rates[toCurrency]*document.getElementById("fromQuantity").value;
})
.catch(function(error) {
console.log(error);
});
}
function convertDineroTop() {
var fromCurrency = document.getElementById("from").value;
var toCurrency = document.getElementById("to").value;
fetch("https://api.exchangeratesapi.io/latest?base=" + toCurrency)
.then((resp) => resp.json())
.then(function(data){
(toCurrency===fromCurrency) ? document.getElementById("fromQuantity").value = document.getElementById("toQuantity").value :
document.getElementById("fromQuantity").value = data.rates[fromCurrency]*document.getElementById("toQuantity").value;
})
.catch(function(error) {
console.log(error);
});
}
$(function() {
var selectBox = $("select").selectBoxIt();
});
</script>
</body>
</html>

额外说明 #

如果你不想用!important，也可以调整#containerSelect的CSS，让flex布局只作用于原始的<select>元素，比如给两个select加个共同的类，然后用#containerSelect .select-class来设置flex子元素样式，这样插件生成的动态元素就不会继承flex布局了。不过上面的方案更直接，能快速解决问题。

内容的提问来源于stack exchange，提问作者silver_hoodlum