fetch('图片地址')
            .then(response => response.blob())
            .then(res => {
               this.$downloadFile('邀请二维码',res)
            });
 Vue.prototype.$downloadFile = function (fileName, blob) {
				const link = document.createElement("a");
				link.href = window.URL.createObjectURL(blob);
				link.download = fileName;
				link.click();
				link.remove();
				window.URL.revokeObjectURL(link.href);
      	}