如何使用getElementsByClassName确定所选下拉选项的值? [英] How can I determine the value of the selected dropdown option using getElementsByClassName?

问题描述

如何使用javascript确定所选下拉选项的值.我无法使用ID选择器，因此我尝试使用document.getElementsByClassName.我了解这会返回一组值.这是我尝试使用的简化代码:

How can I determine the value of the selected dropdown options using javascript. I can't use id selector so I was trying with document.getElementsByClassName. I understand that returns a set of values. Here is a simplified code I am trying to use:

<div id="MDL" class="dates">
<p>Select Dates and Price</p>
<select class="datevalue">
    <option value="30">17th July - &pound;30</option>
    <option value="45">17th July - &pound;45</option>
    <option value="70">17th July - &pound;70</option>
    <option value="30">18th July - &pound;30</option>
    <option value="45">18th July - &pound;45</option>
    <option value="70">18th July - &pound;70</option>
</select>
</div>
<input type="button" id="book" VALUE="Buy Now" onClick="book()">

function book() {
var e = document.getElementsByClassName('datevalue');
alert(e.options[.selectedIndex].value);

}

但是它不起作用.我已将所有相关问题都涂成红色，因此请不要向我发送其他问题的链接.

But it doesn't work. I've red all the related questions so please do not send me a link to an other question.

推荐答案

document.getElementsByClassName 返回 HTMLCollection .即使您只有一个元素，它也是 e [0] ，而不是 e .

document.getElementsByClassName returns a HTMLCollection. Even if you have just one element, it's e[0], not e.

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