如何以编程方式打开Bootstrap下拉列表

本文介绍了如何以编程方式打开Bootstrap下拉列表的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

当我点击另一个下拉列表的项目时，我正在尝试打开Bootstrap下拉列表。

I'm trying to open a Bootstrap dropdown when I click a item of another dropdown.

想法是从第一个下拉列表中选择一个城市 - 然后该脚本将自动打开带有区域的第二个下拉列表（并仅显示与所选城市相对应的区域）。

The idea is to select a city from the first drop down - then the script will auto open the second dropdown with areas (and show only areas corresponding to the chosen city).

这是我的JS：

$('#sidebar_filter_city li').click(function(){ $('#sidebar_filter_areas').dropdown('toggle'); });

这是HTML：

<div class="dropdown form-control"> <div data-toggle="dropdown" id="sidebar_filter_cities" class="sidebar_filter_menu" data-value="jersey-city">Jersey City<span class="caret caret_sidebar"></span></div> <input type="hidden" name="advanced_city" value="jersey-city"> <ul id="sidebar_filter_city" class="dropdown-menu filter_menu" role="menu" aria-labelledby="sidebar_filter_cities"> <li role="presentation" data-value="">All Cities</li> <li role="presentation" data-value="jersey-city">Jersey City</li> <li role="presentation" data-value="london">London</li> <li role="presentation" data-value="new-york">New York</li> </ul> </div> </div> <div class="dropdown form-control"> <div data-toggle="dropdown" id="sidebar_filter_areas" class="sidebar_filter_menu">All Areas<span class="caret caret_sidebar"></span> </div> <input type="hidden" name="advanced_area" value=""> <ul id="sidebar_filter_area" class="dropdown-menu filter_menu" role="menu" aria-labelledby="sidebar_filter_areas"> <li role="presentation" data-value="">All Areas</li> <li role="presentation" data-value="east-harlem" data-parentcity="">East Harlem</li> <li role="presentation" data-value="greenville" data-parentcity="">Greenville</li> <li role="presentation" data-value="manhattan" data-parentcity="">Manhattan</li> <li role="presentation" data-value="northern-brooklyn" data-parentcity="">Northern Brooklyn</li> ..... </ul> </div> </div>

推荐答案

最好的方法是检查下拉列表是否不是已打开，然后使用 .dropdown（'toggle'）。

The best way is to check if the dropdown is not already open, and then to use .dropdown('toggle').

要注意的事项：

• 如果你想触发它通过点击另一个元素，你必须杀死另一个元素上的click事件 - 否则Bootstrap将视为下拉列表外的点击并立即关闭它。 / li>
• $（'。dropdown'）。addClass（'open'）不是 $（'。dropdown-toggle'）。dropdown（'toggle'）按照其他答案中的建议，因为它会导致下拉列表永久保持打开而不是在单击组件时关闭。

• If you want to trigger it by clicking on another element, you must kill the click event on the other element- otherwise Bootstrap will treat it as a click outside of the dropdown and immediately close it.
• $('.dropdown').addClass('open') is not a good replacement for $('.dropdown-toggle').dropdown('toggle') as suggested in other answers, because it will cause the dropdown to stay permanently open instead of closing when you click off of the component.

HTML：

<button class="btn btn-secondary trigger_button">Trigger dropdown</button><br><br> <div class="dropdown"> <button class="btn btn-secondary dropdown-toggle" type="button" data-toggle="dropdown"> Dropdown </button> <div class="dropdown-menu"> Stuff... </div> </div>

JS：

$('.trigger_button').click(function(e){ // Kill click event: e.stopPropagation(); // Toggle dropdown if not already visible: if ($('.dropdown').find('.dropdown-menu').is(":hidden")){ $('.dropdown-toggle').dropdown('toggle'); } });

小提琴示例