diff --git a/src/display/transport_stream.js b/src/display/transport_stream.js
index 32d916307..04b7a7c70 100644
--- a/src/display/transport_stream.js
+++ b/src/display/transport_stream.js
@@ -12,12 +12,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+/* eslint no-var: error */
 
 import { assert, createPromiseCapability } from '../shared/util';
 
- /** @implements {IPDFStream} */
-var PDFDataTransportStream = (function PDFDataTransportStreamClosure() {
-  function PDFDataTransportStream(params, pdfDataRangeTransport) {
+/** @implements {IPDFStream} */
+class PDFDataTransportStream {
+  constructor(params, pdfDataRangeTransport) {
     assert(pdfDataRangeTransport);
 
     this._queuedChunks = [];
@@ -25,7 +26,7 @@ var PDFDataTransportStream = (function PDFDataTransportStreamClosure() {
 
     const initialData = params.initialData;
     if (initialData && initialData.length > 0) {
-      let buffer = new Uint8Array(initialData).buffer;
+      const buffer = new Uint8Array(initialData).buffer;
       this._queuedChunks.push(buffer);
     }
 
@@ -55,95 +56,93 @@ var PDFDataTransportStream = (function PDFDataTransportStreamClosure() {
 
     this._pdfDataRangeTransport.transportReady();
   }
-  PDFDataTransportStream.prototype = {
-    _onReceiveData: function PDFDataTransportStream_onReceiveData(args) {
-       let buffer = new Uint8Array(args.chunk).buffer;
-       if (args.begin === undefined) {
-         if (this._fullRequestReader) {
-           this._fullRequestReader._enqueue(buffer);
-         } else {
-           this._queuedChunks.push(buffer);
-         }
-       } else {
-         var found = this._rangeReaders.some(function (rangeReader) {
-           if (rangeReader._begin !== args.begin) {
-             return false;
-           }
-           rangeReader._enqueue(buffer);
-           return true;
-         });
-         assert(found);
-       }
-    },
 
-    get _progressiveDataLength() {
-      return (this._fullRequestReader ? this._fullRequestReader._loaded : 0);
-    },
-
-    _onProgress: function PDFDataTransportStream_onDataProgress(evt) {
-      if (evt.total === undefined) {
-        // Reporting to first range reader, if it exists.
-        let firstReader = this._rangeReaders[0];
-        if (firstReader && firstReader.onProgress) {
-          firstReader.onProgress({ loaded: evt.loaded, });
-        }
+  _onReceiveData(args) {
+    const buffer = new Uint8Array(args.chunk).buffer;
+    if (args.begin === undefined) {
+      if (this._fullRequestReader) {
+        this._fullRequestReader._enqueue(buffer);
       } else {
-        let fullReader = this._fullRequestReader;
-        if (fullReader && fullReader.onProgress) {
-          fullReader.onProgress({ loaded: evt.loaded, total: evt.total, });
+        this._queuedChunks.push(buffer);
+      }
+    } else {
+      const found = this._rangeReaders.some(function(rangeReader) {
+        if (rangeReader._begin !== args.begin) {
+          return false;
         }
-      }
-    },
-
-    _onProgressiveDone() {
-      if (this._fullRequestReader) {
-        this._fullRequestReader.progressiveDone();
-      }
-      this._progressiveDone = true;
-    },
-
-    _removeRangeReader:
-        function PDFDataTransportStream_removeRangeReader(reader) {
-      var i = this._rangeReaders.indexOf(reader);
-      if (i >= 0) {
-        this._rangeReaders.splice(i, 1);
-      }
-    },
-
-    getFullReader: function PDFDataTransportStream_getFullReader() {
-      assert(!this._fullRequestReader);
-      var queuedChunks = this._queuedChunks;
-      this._queuedChunks = null;
-      return new PDFDataTransportStreamReader(this, queuedChunks,
-                                              this._progressiveDone);
-    },
-
-    getRangeReader: function PDFDataTransportStream_getRangeReader(begin, end) {
-      if (end <= this._progressiveDataLength) {
-        return null;
-      }
-      var reader = new PDFDataTransportStreamRangeReader(this, begin, end);
-      this._pdfDataRangeTransport.requestDataRange(begin, end);
-      this._rangeReaders.push(reader);
-      return reader;
-    },
-
-    cancelAllRequests:
-        function PDFDataTransportStream_cancelAllRequests(reason) {
-      if (this._fullRequestReader) {
-        this._fullRequestReader.cancel(reason);
-      }
-      var readers = this._rangeReaders.slice(0);
-      readers.forEach(function (rangeReader) {
-        rangeReader.cancel(reason);
+        rangeReader._enqueue(buffer);
+        return true;
       });
-      this._pdfDataRangeTransport.abort();
-    },
-  };
+      assert(found);
+    }
+  }
 
-  /** @implements {IPDFStreamReader} */
-  function PDFDataTransportStreamReader(stream, queuedChunks,
-                                        progressiveDone = false) {
+  get _progressiveDataLength() {
+    return (this._fullRequestReader ? this._fullRequestReader._loaded : 0);
+  }
+
+  _onProgress(evt) {
+    if (evt.total === undefined) {
+      // Reporting to first range reader, if it exists.
+      const firstReader = this._rangeReaders[0];
+      if (firstReader && firstReader.onProgress) {
+        firstReader.onProgress({ loaded: evt.loaded, });
+      }
+    } else {
+      const fullReader = this._fullRequestReader;
+      if (fullReader && fullReader.onProgress) {
+        fullReader.onProgress({ loaded: evt.loaded, total: evt.total, });
+      }
+    }
+  }
+
+  _onProgressiveDone() {
+    if (this._fullRequestReader) {
+      this._fullRequestReader.progressiveDone();
+    }
+    this._progressiveDone = true;
+  }
+
+  _removeRangeReader(reader) {
+    const i = this._rangeReaders.indexOf(reader);
+    if (i >= 0) {
+      this._rangeReaders.splice(i, 1);
+    }
+  }
+
+  getFullReader() {
+    assert(!this._fullRequestReader);
+    const queuedChunks = this._queuedChunks;
+    this._queuedChunks = null;
+    return new PDFDataTransportStreamReader(this, queuedChunks,
+                                            this._progressiveDone);
+  }
+
+  getRangeReader(begin, end) {
+    if (end <= this._progressiveDataLength) {
+      return null;
+    }
+    const reader = new PDFDataTransportStreamRangeReader(this, begin, end);
+    this._pdfDataRangeTransport.requestDataRange(begin, end);
+    this._rangeReaders.push(reader);
+    return reader;
+  }
+
+  cancelAllRequests(reason) {
+    if (this._fullRequestReader) {
+      this._fullRequestReader.cancel(reason);
+    }
+    const readers = this._rangeReaders.slice(0);
+    readers.forEach(function(rangeReader) {
+      rangeReader.cancel(reason);
+    });
+    this._pdfDataRangeTransport.abort();
+  }
+}
+
+/** @implements {IPDFStreamReader} */
+class PDFDataTransportStreamReader {
+  constructor(stream, queuedChunks, progressiveDone = false) {
     this._stream = stream;
     this._done = progressiveDone || false;
     this._filename = null;
@@ -156,73 +155,74 @@ var PDFDataTransportStream = (function PDFDataTransportStreamClosure() {
     this._headersReady = Promise.resolve();
     stream._fullRequestReader = this;
 
-    this.onProgress = null; // not used
+    this.onProgress = null;
   }
-  PDFDataTransportStreamReader.prototype = {
-    _enqueue: function PDFDataTransportStreamReader_enqueue(chunk) {
-      if (this._done) {
-        return; // ignore new data
-      }
-      if (this._requests.length > 0) {
-        var requestCapability = this._requests.shift();
-        requestCapability.resolve({ value: chunk, done: false, });
-      } else {
-        this._queuedChunks.push(chunk);
-      }
-      this._loaded += chunk.byteLength;
-    },
 
-    get headersReady() {
-      return this._headersReady;
-    },
+  _enqueue(chunk) {
+    if (this._done) {
+      return; // Ignore new data.
+    }
+    if (this._requests.length > 0) {
+      const requestCapability = this._requests.shift();
+      requestCapability.resolve({ value: chunk, done: false, });
+    } else {
+      this._queuedChunks.push(chunk);
+    }
+    this._loaded += chunk.byteLength;
+  }
 
-    get filename() {
-      return this._filename;
-    },
+  get headersReady() {
+    return this._headersReady;
+  }
 
-    get isRangeSupported() {
-      return this._stream._isRangeSupported;
-    },
+  get filename() {
+    return this._filename;
+  }
 
-    get isStreamingSupported() {
-      return this._stream._isStreamingSupported;
-    },
+  get isRangeSupported() {
+    return this._stream._isRangeSupported;
+  }
 
-    get contentLength() {
-      return this._stream._contentLength;
-    },
+  get isStreamingSupported() {
+    return this._stream._isStreamingSupported;
+  }
 
-    async read() {
-      if (this._queuedChunks.length > 0) {
-        var chunk = this._queuedChunks.shift();
-        return { value: chunk, done: false, };
-      }
-      if (this._done) {
-        return { value: undefined, done: true, };
-      }
-      var requestCapability = createPromiseCapability();
-      this._requests.push(requestCapability);
-      return requestCapability.promise;
-    },
+  get contentLength() {
+    return this._stream._contentLength;
+  }
 
-    cancel: function PDFDataTransportStreamReader_cancel(reason) {
-      this._done = true;
-      this._requests.forEach(function (requestCapability) {
-        requestCapability.resolve({ value: undefined, done: true, });
-      });
-      this._requests = [];
-    },
+  async read() {
+    if (this._queuedChunks.length > 0) {
+      const chunk = this._queuedChunks.shift();
+      return { value: chunk, done: false, };
+    }
+    if (this._done) {
+      return { value: undefined, done: true, };
+    }
+    const requestCapability = createPromiseCapability();
+    this._requests.push(requestCapability);
+    return requestCapability.promise;
+  }
 
-    progressiveDone() {
-      if (this._done) {
-        return;
-      }
-      this._done = true;
-    },
-  };
+  cancel(reason) {
+    this._done = true;
+    this._requests.forEach(function(requestCapability) {
+      requestCapability.resolve({ value: undefined, done: true, });
+    });
+    this._requests = [];
+  }
 
-  /** @implements {IPDFStreamRangeReader} */
-  function PDFDataTransportStreamRangeReader(stream, begin, end) {
+  progressiveDone() {
+    if (this._done) {
+      return;
+    }
+    this._done = true;
+  }
+}
+
+/** @implements {IPDFStreamRangeReader} */
+class PDFDataTransportStreamRangeReader {
+  constructor(stream, begin, end) {
     this._stream = stream;
     this._begin = begin;
     this._end = end;
@@ -232,55 +232,52 @@ var PDFDataTransportStream = (function PDFDataTransportStreamClosure() {
 
     this.onProgress = null;
   }
-  PDFDataTransportStreamRangeReader.prototype = {
-    _enqueue: function PDFDataTransportStreamRangeReader_enqueue(chunk) {
-      if (this._done) {
-        return; // ignore new data
-      }
-      if (this._requests.length === 0) {
-        this._queuedChunk = chunk;
-      } else {
-        var requestsCapability = this._requests.shift();
-        requestsCapability.resolve({ value: chunk, done: false, });
-        this._requests.forEach(function (requestCapability) {
-          requestCapability.resolve({ value: undefined, done: true, });
-        });
-        this._requests = [];
-      }
-      this._done = true;
-      this._stream._removeRangeReader(this);
-    },
 
-    get isStreamingSupported() {
-      return false;
-    },
-
-    async read() {
-      if (this._queuedChunk) {
-        let chunk = this._queuedChunk;
-        this._queuedChunk = null;
-        return { value: chunk, done: false, };
-      }
-      if (this._done) {
-        return { value: undefined, done: true, };
-      }
-      var requestCapability = createPromiseCapability();
-      this._requests.push(requestCapability);
-      return requestCapability.promise;
-    },
-
-    cancel: function PDFDataTransportStreamRangeReader_cancel(reason) {
-      this._done = true;
-      this._requests.forEach(function (requestCapability) {
+  _enqueue(chunk) {
+    if (this._done) {
+      return; // ignore new data
+    }
+    if (this._requests.length === 0) {
+      this._queuedChunk = chunk;
+    } else {
+      const requestsCapability = this._requests.shift();
+      requestsCapability.resolve({ value: chunk, done: false, });
+      this._requests.forEach(function(requestCapability) {
         requestCapability.resolve({ value: undefined, done: true, });
       });
       this._requests = [];
-      this._stream._removeRangeReader(this);
-    },
-  };
+    }
+    this._done = true;
+    this._stream._removeRangeReader(this);
+  }
 
-  return PDFDataTransportStream;
-})();
+  get isStreamingSupported() {
+    return false;
+  }
+
+  async read() {
+    if (this._queuedChunk) {
+      const chunk = this._queuedChunk;
+      this._queuedChunk = null;
+      return { value: chunk, done: false, };
+    }
+    if (this._done) {
+      return { value: undefined, done: true, };
+    }
+    const requestCapability = createPromiseCapability();
+    this._requests.push(requestCapability);
+    return requestCapability.promise;
+  }
+
+  cancel(reason) {
+    this._done = true;
+    this._requests.forEach(function(requestCapability) {
+      requestCapability.resolve({ value: undefined, done: true, });
+    });
+    this._requests = [];
+    this._stream._removeRangeReader(this);
+  }
+}
 
 export {
   PDFDataTransportStream,