使用jQuery设置Dropdown的选定索引 [英] Set the selected index of a Dropdown using jQuery

问题描述

如果我找到控件的方式如下，如何在jQuery中设置下拉列表的索引:

How do I set the index of a dropdown in jQuery if the way I'm finding the control is as follows:

$("*[id$='" + originalId + "']") 

之所以这样做是因为我是动态创建控件的，并且由于使用Web Forms时ID会更改，因此我发现这是一种为我找到一些控件的方法.但是一旦有了jQuery对象，就不知道如何将所选索引设置为0(零).

I do it this way because I'm creating controls dynamically and since the ids are changed when using Web Forms, I found this as a work around to find me some controls. But once I have the jQuery object, I do not know how to set the selected index to 0 (zero).

推荐答案

首先-选择器非常慢.它将扫描每个DOM元素以查找ID.如果您可以为元素分配一个类，则对性能的影响较小.

First of all - that selector is pretty slow. It will scan every DOM element looking for the ids. It will be less of a performance hit if you can assign a class to the element.

$(".myselect")

尽管要回答您的问题，但是有几种方法可以更改jQuery中的select元素值

To answer your question though, there are a few ways to change the select elements value in jQuery

// sets selected index of a select box to the option with the value "0"
$("select#elem").val('0'); 

// sets selected index of a select box to the option with the value ""
$("select#elem").val(''); 

// sets selected index to first item using the DOM
$("select#elem")[0].selectedIndex = 0;

// sets selected index to first item using jQuery (can work on multiple elements)
$("select#elem").prop('selectedIndex', 0);

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