download(url) {
      var filename = "";
      var name = url.split("/")[url.split("/").length - 1];
      if (name.indexOf(".copy") != "-1") {
        filename = name.split(".copy")[0];
      } else {
        filename = name;
      }
      return fetch(url).then((res) =>
        res.blob().then((blob) => {
          let a = document.createElement("a");
          let url = window.URL.createObjectURL(blob);
          if (window.navigator.msSaveBlob) {
            // ie下载
            try {
              window.navigator.msSaveBlob(blob, filename);
            } catch (e) {
              console.log(e);
            }
          } else {
            // 其他下载
            a.href = url;
            a.download = filename;
            a.click();
            window.URL.revokeObjectURL(url);
          }
        })
      );
    },

es6兼容fetch

npm install --save isomorphic-fetch es6-promise
import "isomorphic-fetch"