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Javascript 如何在第二次选择中自动选择与第一次选择相同的数值选项?_Javascript_Php_Twitter Bootstrap_Select - Fatal编程技术网

Javascript 如何在第二次选择中自动选择与第一次选择相同的数值选项?

Javascript 如何在第二次选择中自动选择与第一次选择相同的数值选项?,javascript,php,twitter-bootstrap,select,Javascript,Php,Twitter Bootstrap,Select,新的引导和JavaScript <select id="list1" name="list1" class="form-control" required/> <?php for ($h = 1; $h <= 7; $h++) echo "<option value='$h'>$h</option>"; ?> </select> <select id="list2" name="list2" class="form-co

新的引导和JavaScript

<select id="list1" name="list1" class="form-control" required/>
<?php
for ($h = 1; $h <= 7; $h++) echo "<option value='$h'>$h</option>";
?>
</select>


<select id="list2" name="list2" class="form-control" required/>
<?php
for ($h = 1; $h <= 7; $h++) echo "<option value='$h'>$h</option>";
?>
</select>

您可以使用
HTMLSelectElement
的属性:

const firstList=document.getElementById('list1');
const secondList=document.getElementById('list2');
firstList.addEventListener('change',()=>{
secondList.selectedIndex=firstList.selectedIndex;
});

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您可以使用
HTMLSelectElement
的属性:

const firstList=document.getElementById('list1');
const secondList=document.getElementById('list2');
firstList.addEventListener('change',()=>{
secondList.selectedIndex=firstList.selectedIndex;
});

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