子组件：

<template>
	<div>
	<input class="form-control autoSelect" type="text" @mouseup="mouse" @keyup="loadOptions" v-model="selectContent" />
	<div class="autoSelectDiv" isHover="false" v-show="isShow">
		<ul>
			<li v-for="dataItem in selectList" @click="selectItem(dataItem)">{{dataItem.vName}}</li>
		</ul>
	</div>
	</div>
</template>

<script type="text/javascript">
	export default{
		name:'autoSelect',
		props:{ 

                        //父级传过来的默认被选中的值

			name:{
				type:String,
				default:''
			},
			url:{
				type: String,
            			default:''
			}
                },
		data(){
			return{								
				returnContent:{selectedId:'',flag:0,selectContent:''},//我多个地方调用了下拉菜单，所以加了一个flag区分		
				selectList:[],
				isShow:false
			}
		},
		mounted(){
			//点击其他地方，隐藏下拉菜单
			this.bodyLister=(e)=>{
					if(this.isShow==true){
					this.isShow=false;
				}
			}
			document.addEventListener('click',this.bodyLister);
		},
		watch:{
			name:{
				handler:function (newValue, oldValue) {
					this.returnContent.selectContent=newValue;
				}
			}
		},
		methods:{			
			selectItem(data){
				this.returnContent.selectedId=data.vCode;
				this.returnContent.selectContent=data.vName;
				this.isShow=false;
				this.$emit('getAutoSelectResult',this.returnContent);
			},
			mouse(){  //点击输入框时就发送请求
				if(this.selectContent==""){
					this.loadOptions();
				}
			},
			loadOptions(){
				var _this=this;var parameter={};
				switch(_this.url){
					case 'url1':
						parameter['param1']='要传的参数1';
						this.returnContent.flag=1;
						break;
					case 'url2':
						parameter['param2']='要传的参数2';
						this.returnContent.flag=2;
						break;
						
				}
				parameter['name']=this.returnContent.selectContent;
				//请求接口去吧
				doRequest(url,parameter,function(result){					
					for(var i=0;i<result.length;i++){						
						_this.selectList.push({vCode:obj[i].value,vName:obj[i].name});
					}
					_this.isShow=true;
				})
			}
		}
	}

父组件：

<autoSelect :url="要请求的url" :name="要默认显示的值" @getAutoSelectResult="listenAutoSelectResult"></autoSelect>