Synchronous operation [Use of promise, async, await]

Example 1:

 methods:{
    before (file) {
      console.log('文件', file)
      return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.readAsDataURL(file);
        reader.onload = function () {
          // 图片转base64完成后返回reader对象
          //this.smallbase64 = reader.result;
          console.log('文件2', reader.result)
          resolve(reader.result);
        };
      });
    },
    async upload (item) {
      console.log(item)
      this.addBook.coverUrl = await this.before(item.raw);

      let parames = {
        functionName: "productbiz.service.puhui.UpdatePictureService",
        methodName: "uploadImage",
        data: {
          coverImage: this.addBook.coverUrl,
          userId: JSON.parse(sessionStorage.getItem('sessionData')).userId
        }
      };
      console.log(222, parames);
      this.http(JSON.stringify(parames))
        .then(res => {
          console.log(res.data.path)
          this.addBook.coverUrl = res.data.path
        })
        .catch(res => { });
    },
}

Example 2:

getSelectTemplateInfo(id) {
      // 获得模板详细信息
      return new Promise(resolve => {
        let parames = {
          functionName: "marketingTemplateService",
          methodName: "selectMarketingTemplateInfo",
          pageNo: 1,
          pageSize: 10,
          originSource: {
            OS: this.OS,
            version: "h5_v2.0"
          },
          data: {
            templateId: id
          }
        };
        this.$post(JSON.stringify(parames)).then(result => {
          if (result.errorCode == ERROR_CODE && result.data.codeType == 200) {
            // console.log('详情',result.data.templateInfo)
            resolve(result.data.templateInfo);
          }
        });
      });
    },

async selectTemplate(item, index) {
      let info = await this.getSelectTemplateInfo(item.id);
      if (this.selectedTempProduct == null) {
        // 未选择产品
        this.SET_SELECTEDTEMP(info);
        this.selectedTempIndex = index;
        console.log("选中模板", index, this.selectedTemp);
      } else {
        // 选择产品后切换模板判断模板类型
        if (this.selectedTempProduct.productType != item.prdType) {
          Dialog.confirm({
            // title: "选择产品提示",
            confirmButtonText: "确定",
            confirmButtonColor: "#DE1716",
            width: "288",
            className: "confirmStyle",
            message: "您选择的产品不适用于该模板，切换后需要重新选择产品"
          })
            .then(() => {
              this.clearProduct();
              this.SET_SELECTEDTEMP(info);
              this.selectedTempIndex = index;
            })
            .catch(() => {
              console.log("取消");
            });
        }else{
           this.SET_SELECTEDTEMP(info);
           this.selectedTempIndex = index;
        }
        console.log("选中模板", index, this.selectedTemp);
      }
    },