js 缓存视频文件到本地

         blobLoad(src, obj) {
            let self = this;
            const req = new XMLHttpRequest();
            req.open("GET", src, true);
            req.responseType = "blob";
            req.onload = function () {
              // Onload is triggered even on 404
              // so we need to check the status code
              if (this.status === 200) {
                const videoBlob = this.response;
                const blobSrc = URL.createObjectURL(videoBlob); // IE10+
                // Video is now downloaded
                // and we can set it as source on the video element
                // blobSrc 便是虚拟的本地地址
              }
            };
            req.onerror = function () {
              // Error
            };
            req.send();
          },

　　可通过 ajax 请求将文件缓存为本地 blob，并由 URL.createObjectURL 缓存到本地。之后使用 blobSrc 作为静态资源地址即可。blobSrc 的生存周期与页面一致。