async ... await

promise寫法

function runAsync1(){
            var p = new Promise(function(resolve, reject){
                //作一些異步操做
                setTimeout(function(){
                    console.log('異步任務1執行完成');
                    resolve('隨便什麼數據1');
                }, 1000);
            });
            return p;
        }
        function runAsync2(){
            var p = new Promise(function(resolve, reject){
                //作一些異步操做
                setTimeout(function(){
                    console.log('異步任務2執行完成');
                    resolve('隨便什麼數據2');
                }, 2000);
            });
            return p;
        }
        function runAsync3(){
            var p = new Promise(function(resolve, reject){
                //作一些異步操做
                setTimeout(function(){
                    console.log('異步任務3執行完成');
                    resolve('隨便什麼數據3');
                }, 2000);
            });
            return p;
        }

        runAsync1()
                .then(function(data){
                    console.log(data);
                    return runAsync2();
                })
                .then(function(data){
                    console.log(data);
                    return runAsync3();
                })
                .then(function(data){
                    console.log(data);
                });

1. 包裝多個promise對象 

2. 多個異步操做 要在回調裏 return下一個promise對象  ，操做多了，回調也是有點麻煩 

==============

async 寫法

用同步的方式 寫異步操做

獲取部門數據時，必須是return 異步對象

若是return res = this.$ajax...     這樣會有問題 取值 undefined

getDeptData(){ //獲取部門數據
				return this.$ajax({
					url: this.$ajax.apiUrl("/sys/dept/list"),
					method: "get",
					params: this.$ajax.adornParams()
				});
			},

			getRolesData(){ //獲取角色數據
				return  this.$ajax({
					url: this.$ajax.apiUrl("/sys/role/all"),
					method: "get",
					params: this.$ajax.adornParams()
				});

			},

			async init(id){
				try{
					let res_dept = await this.getDeptData();
					let res_role = await this.getRolesData();

					this.deptList = this.$tool.treeDataTranslate(res_dept.data);
					this.roleList = res_role.data;
					this.dataForm.id = id;
					this.isEdit=false,

					this.visible = true;
					this.$nextTick(() => {
						this.$refs["dataForm"].resetFields();
					});


					if (!id) {// 新增
						this.dataForm.deptName = null;
						console.log('新增', this.dataForm)
					} else {// 修改
						this.isEdit = true;

						this.$ajax({
							url: this.$ajax.apiUrl(`/sys/user/detail`),
							method: "get",
							params: this.$ajax.adornParams({
								id: this.dataForm.id
							})
						}).then(({data}) => {
							console.log('詳情', data);
							this.dataForm.deptId = data.deptId;
							this.dataForm.loginName = data.loginName;
							this.dataForm.phoneNumber = data.phoneNumber;
							this.dataForm.remark = data.remark;
							this.dataForm.roleId = data.roleId;
							this.dataForm.status = data.status;
							this.dataForm.userName = data.userName;

							this.dataForm.id = id;
							this.deptListTreeSetCurrentNode();

						});
					}
				} catch(err){
					console.log(err)
				}
			},