Javascript 使用 JS 从列表中获取所选项目
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Get selected Item from the list with JS
提问by Alex
I have an html list with some items loaded. I am able to get the select list object using the following code:
我有一个 html 列表，其中加载了一些项目。我可以使用以下代码获取选择列表对象：
var list = document.getElementById('ddlReason');
but I need help with figuring out how to detect which value has been chosen from the list.
但我需要帮助弄清楚如何检测从列表中选择了哪个值。
回答by Erik
// Gets your select
var list = document.getElementById('ddlReason');
// Get the index of selected item, first item 0, second item 1 etc ...
var INDEX = list.selectedIndex;
// Viola you're done
alert(list[INDEX].value);
Edit (forgot .value).
编辑（忘记 .value）。
You can also make that a bit more concise, but I wanted to make it readable so you could see what was going on. Shorter version:
你也可以让它更简洁一点，但我想让它可读，这样你就可以看到发生了什么。较短的版本：
var list = document.getElementById('ddlReason');
alert(list[list.selectedIndex].value);
回答by user3381402
Actually you can do this
其实你可以这样做
var list = document.getElementById('ddlReason').value;
and if you make an alert to list, you'll get the value of your select tag.
如果您向 发出警报list，您将获得 select 标签的值。
回答by Scott Saunders
The list object will have a 'options' attribute that is an array of all the options in the list and a 'selectedIndex' attribute that contains the index of the selected item (or the first selected item if there are multiple). So you can do this:
列表对象将有一个 'options' 属性，它是列表中所有选项的数组，以及一个 'selectedIndex' 属性，它包含所选项目的索引（如果有多个，则为第一个所选项目）。所以你可以这样做：
var list = document.getElementById('ddlReason');
var selectedValue = list.options[list.selectedIndex];
