docs: function loadURLasArrayBuffer(path, callback) {
      if (path.indexOf("data:") === 0) {
          var offset = path.indexOf("base64,") + 7;
          var data = atob(path.substring(offset));
          var arr = new Uint8Array(data.length);
          for (var i = data.length - 1; i >= 0; i--) {
              arr[i] = data.charCodeAt(i);
          }
          callback(arr.buffer);
          return;
      }
      var xhr = new XMLHttpRequest();
      xhr.open("GET", path, true);
      xhr.responseType = "arraybuffer";
      xhr.onload = function () {
          callback(xhr.response);
      };
      xhr.send(null);
  }