ElementUI浅尝辄止28：Dropdown 下拉菜单

将动作或菜单折叠到下拉菜单中。

1.如何使用？

移动到下拉菜单上，展开更多操作。

//通过组件slot来设置下拉触发的元素以及需要通过具名slot为dropdown 来设置下拉菜单。默认情况下，下拉按钮只要hover即可，无需点击也会显示下拉菜单。<el-dropdown><span class="el-dropdown-link">下拉菜单<i class="el-icon-arrow-down el-icon--right"></i></span><el-dropdown-menu slot="dropdown"><el-dropdown-item>黄金糕</el-dropdown-item><el-dropdown-item>狮子头</el-dropdown-item><el-dropdown-item>螺蛳粉</el-dropdown-item><el-dropdown-item disabled>双皮奶</el-dropdown-item><el-dropdown-item divided>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown><style>.el-dropdown-link {cursor: pointer;color: #409EFF;}.el-icon-arrow-down {font-size: 12px;}
</style>

2.触发对象

可使用按钮触发下拉菜单。

//设置split-button属性来让触发下拉元素呈现为按钮组，左边是功能按钮，右边是触发下拉菜单的按钮，设置为true即可。<el-dropdown><el-button type="primary">更多菜单<i class="el-icon-arrow-down el-icon--right"></i></el-button><el-dropdown-menu slot="dropdown"><el-dropdown-item>黄金糕</el-dropdown-item><el-dropdown-item>狮子头</el-dropdown-item><el-dropdown-item>螺蛳粉</el-dropdown-item><el-dropdown-item>双皮奶</el-dropdown-item><el-dropdown-item>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown>
<el-dropdown split-button type="primary" @click="handleClick">更多菜单<el-dropdown-menu slot="dropdown"><el-dropdown-item>黄金糕</el-dropdown-item><el-dropdown-item>狮子头</el-dropdown-item><el-dropdown-item>螺蛳粉</el-dropdown-item><el-dropdown-item>双皮奶</el-dropdown-item><el-dropdown-item>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown><style>.el-dropdown {vertical-align: top;}.el-dropdown + .el-dropdown {margin-left: 15px;}.el-icon-arrow-down {font-size: 12px;}
</style><script>export default {methods: {handleClick() {alert('button click');}}}
</script>

3.触发方式

可以配置 click 激活或者 hover 激活。

在trigger属性设置为click即可。<el-row class="block-col-2"><el-col :span="12"><span class="demonstration">hover 激活</span><el-dropdown><span class="el-dropdown-link">下拉菜单<i class="el-icon-arrow-down el-icon--right"></i></span><el-dropdown-menu slot="dropdown"><el-dropdown-item icon="el-icon-plus">黄金糕</el-dropdown-item><el-dropdown-item icon="el-icon-circle-plus">狮子头</el-dropdown-item><el-dropdown-item icon="el-icon-circle-plus-outline">螺蛳粉</el-dropdown-item><el-dropdown-item icon="el-icon-check">双皮奶</el-dropdown-item><el-dropdown-item icon="el-icon-circle-check">蚵仔煎</el-dropdown-item></el-dropdown-menu></el-dropdown></el-col><el-col :span="12"><span class="demonstration">click 激活</span><el-dropdown trigger="click"><span class="el-dropdown-link">下拉菜单<i class="el-icon-arrow-down el-icon--right"></i></span><el-dropdown-menu slot="dropdown"><el-dropdown-item icon="el-icon-plus">黄金糕</el-dropdown-item><el-dropdown-item icon="el-icon-circle-plus">狮子头</el-dropdown-item><el-dropdown-item icon="el-icon-circle-plus-outline">螺蛳粉</el-dropdown-item><el-dropdown-item icon="el-icon-check">双皮奶</el-dropdown-item><el-dropdown-item icon="el-icon-circle-check">蚵仔煎</el-dropdown-item></el-dropdown-menu></el-dropdown></el-col>
</el-row><style>.el-dropdown-link {cursor: pointer;color: #409EFF;}.el-icon-arrow-down {font-size: 12px;}.demonstration {display: block;color: #8492a6;font-size: 14px;margin-bottom: 20px;}
</style>

4.菜单隐藏方式

可以hide-on-click属性来配置。

//下拉菜单默认在点击菜单项后会被隐藏，将hide-on-click属性默认为false可以关闭此功能。<el-dropdown :hide-on-click="false"><span class="el-dropdown-link">下拉菜单<i class="el-icon-arrow-down el-icon--right"></i></span><el-dropdown-menu slot="dropdown"><el-dropdown-item>黄金糕</el-dropdown-item><el-dropdown-item>狮子头</el-dropdown-item><el-dropdown-item>螺蛳粉</el-dropdown-item><el-dropdown-item disabled>双皮奶</el-dropdown-item><el-dropdown-item divided>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown><style>.el-dropdown-link {cursor: pointer;color: #409EFF;}.el-icon-arrow-down {font-size: 12px;}
</style>

5.指令事件

点击菜单项后会触发事件，用户可以通过相应的菜单项 key 进行不同的操作

<el-dropdown @command="handleCommand"><span class="el-dropdown-link">下拉菜单<i class="el-icon-arrow-down el-icon--right"></i></span><el-dropdown-menu slot="dropdown"><el-dropdown-item command="a">黄金糕</el-dropdown-item><el-dropdown-item command="b">狮子头</el-dropdown-item><el-dropdown-item command="c">螺蛳粉</el-dropdown-item><el-dropdown-item command="d" disabled>双皮奶</el-dropdown-item><el-dropdown-item command="e" divided>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown><style>.el-dropdown-link {cursor: pointer;color: #409EFF;}.el-icon-arrow-down {font-size: 12px;}
</style><script>export default {methods: {handleCommand(command) {this.$message('click on item ' + command);}}}
</script>

6. 不同尺寸

Dropdown 组件提供除了默认值以外的三种尺寸，可以在不同场景下选择合适的尺寸。

//额外的尺寸：medium、small、mini，通过设置size属性来配置它们。<el-dropdown split-button type="primary">默认尺寸<el-dropdown-menu slot="dropdown"><el-dropdown-item>黄金糕</el-dropdown-item><el-dropdown-item>狮子头</el-dropdown-item><el-dropdown-item>螺蛳粉</el-dropdown-item><el-dropdown-item>双皮奶</el-dropdown-item><el-dropdown-item>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown><el-dropdown size="medium" split-button type="primary">中等尺寸<el-dropdown-menu slot="dropdown"><el-dropdown-item>黄金糕</el-dropdown-item><el-dropdown-item>狮子头</el-dropdown-item><el-dropdown-item>螺蛳粉</el-dropdown-item><el-dropdown-item>双皮奶</el-dropdown-item><el-dropdown-item>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown><el-dropdown size="small" split-button type="primary">小型尺寸<el-dropdown-menu slot="dropdown"><el-dropdown-item>黄金糕</el-dropdown-item><el-dropdown-item>狮子头</el-dropdown-item><el-dropdown-item>螺蛳粉</el-dropdown-item><el-dropdown-item>双皮奶</el-dropdown-item><el-dropdown-item>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown><el-dropdown size="mini" split-button type="primary">超小尺寸<el-dropdown-menu slot="dropdown"><el-dropdown-item>黄金糕</el-dropdown-item><el-dropdown-item>狮子头</el-dropdown-item><el-dropdown-item>螺蛳粉</el-dropdown-item><el-dropdown-item>双皮奶</el-dropdown-item><el-dropdown-item>蚵仔煎</el-dropdown-item></el-dropdown-menu>
</el-dropdown>