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Detailed explanation of Bootstrap drop-down menu examples
- 零下一度Original
- 2017-07-03 11:03:281456browse
Previous words
When interacting with web pages, context menus or hidden/show menu items are often needed. Bootstrap provides a switchable, contextual menu by default for displaying a link list. Moreover, the menu display in various interactive states needs to be used in conjunction with the javascript plug-in. This article will introduce the Bootstrap drop-down menu in detail
How to use
When using the drop-down menu of the Bootstrap framework, you must call the bootstrap.js file provided by the Bootstrap framework. Of course, if you are using the uncompiled version, you can find a file named "dropdown.js" in the js folder, and you can also call this js file
Because Bootstrap's component interaction effects all depend on A plug-in written by the jQuery library, so jquery.js must be loaded before using bootstrap.js to produce the effect
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Document</title><link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css?1.1.11" rel="stylesheet"></head><body><script src="https://cdn.bootcss.com/jquery/1.12.4/jquery.min.js?1.1.11"></script><script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js?1.1.11"></script></body></html>
Basic usage
When using the drop-down menu component in the Bootstrap framework, it is very important to use the correct structure. If the structure and class name are not used correctly, it will directly affect whether the component can be used normally
1. Use a name The container of "dropdown" wraps the entire drop-down menu element
<div class="dropdown"></div>
2. Use a
<button class="btn dropdown-toggle" type="button" data-toggle="dropdown">
3. The drop-down menu item uses a ul list, and defines a class name "dropdown -menu"
<ul class="dropdown-menu" role="menu">
ActionAnother actionSomething else here
.dropup for the parent element of the drop-down menu class, which allows the menu to pop up (the default is to pop down)
<div class="dropup"> <button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="true">Dropup<span class="caret"></span> </button> <ul class="dropdown-menu" aria-labelledby="dropdownMenu1"><li><a href="#">Action</a></li><li><a href="#">Another action</a></li><li><a href="#">Something else here</a></li> </ul></div>
.dropdown-menu {
position: absolute;/*设置绝对定位，相对于父元素div.dropdown*/
top: 100%;/*让下拉菜单项在父菜单项底部，如果父元素不设置相对定位，该元素相对于body元素*/
left: 0;
z-index: 1000;/*让下拉菜单项不被其他元素遮盖住*/
display: none;/*默认隐藏下拉菜单项*/
float: left;
min-width: 160px;
padding: 5px 0;
margin: 2px 0 0;
font-size: 14px;
list-style: none;
background-color: #fff;
background-clip: padding-box;
border: 1px solid #ccc;
border: 1px solid rgba(0, 0, 0, .15);
border-radius: 4px;
-webkit-box-shadow: 0 6px 12px rgba(0, 0, 0, .175);
box-shadow: 0 6px 12px rgba(0, 0, 0, .175);
}
Now let’s analyze the implementation principle. It is very simple. Through js technical means, add or Remove the class name "open" to control the display or hiding of the drop-down menu. That is to say, by default, "div.dropdown" does not have the class name "open". When the user clicks for the first time, "div.dropdown" will add the class name "open"; when the user clicks again, "div.dropdown" "The class name "open" in the container will be removed again
.open > .dropdown-menu {
display: block;
}
Extended usage[Separator line] The drop-down menu in the Bootstrap framework provides a drop-down separator. Assuming that the drop-down menu has two groups, you can add an empty .dropdown-menu .divider {
height: 1px;
margin: 9px 0;
overflow: hidden;
background-color: #e5e5e5;
}
<li role="separator" class="divider"></li>
<li class="dropdown-header">Dropdown header</li>
.dropdown-header {
display: block;
padding: 3px 20px;
font-size: 12px;
line-height: 1.42857143;
color: #999;
}
<div class="dropdown"> <button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="true">Dropdown<span class="caret"></span> </button> <ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1"><li role="presentation" class="dropdown-header">第一部分菜单头部</li><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li><li role="presentation" class="divider"></li><li role="presentation" class="dropdown-header">第二部分菜单头部</li><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li> </ul></div>
.dropdown-menu-right {
right: 0;
left: auto;
}
Since is a block-level element by default, filling the parent width. Here, you need to set inline-block and margin-left for the element so that its content stretches the width and is a certain distance from the left side
In addition to the above two states, the drop-down menu items also have the current state (.active) and the disabled state (.disabled). To use these two states, you only need to add the corresponding class name to the corresponding menu item
display: inline-block; margin-left: 60px;
<div class="dropdown" style="display: inline-block;margin-left: 60px;"> <button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="true">Dropdown<span class="caret"></span> </button> <ul class="dropdown-menu dropdown-menu-right" role="menu" aria-labelledby="dropdownMenu1"><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li><li role="presentation" class="divider"></li><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li> </ul></div>
.dropdown-menu > li > a:hover,
.dropdown-menu > li > a:focus {
color: #262626;
text-decoration: none;
background-color: #f5f5f5;
}
<div class="dropdown"> <button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="true">Dropdown<span class="caret"></span> </button> <ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1"><li role="presentation" class="active"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li><li role="presentation"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li><li role="presentation" class="divider"></li><li role="presentation" class="disabled"><a role="menuitem" tabindex="-1" href="#">下拉菜单项</a></li> </ul></div>
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