diff --git a/src/display/fetch_stream.js b/src/display/fetch_stream.js
index 7dcd3e537..f70ed1d54 100644
--- a/src/display/fetch_stream.js
+++ b/src/display/fetch_stream.js
@@ -12,6 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+/* eslint no-var: error */
 
 import {
   AbortException, assert, createPromiseCapability
@@ -32,6 +33,7 @@ function createFetchOptions(headers, withCredentials, abortController) {
   };
 }
 
+/** @implements {IPDFStream} */
 class PDFFetchStream {
   constructor(source) {
     this.source = source;
@@ -56,7 +58,7 @@ class PDFFetchStream {
     if (end <= this._progressiveDataLength) {
       return null;
     }
-    let reader = new PDFFetchStreamRangeReader(this, begin, end);
+    const reader = new PDFFetchStreamRangeReader(this, begin, end);
     this._rangeRequestReaders.push(reader);
     return reader;
   }
@@ -65,21 +67,22 @@ class PDFFetchStream {
     if (this._fullRequestReader) {
       this._fullRequestReader.cancel(reason);
     }
-    let readers = this._rangeRequestReaders.slice(0);
+    const readers = this._rangeRequestReaders.slice(0);
     readers.forEach(function(reader) {
       reader.cancel(reason);
     });
   }
 }
 
+/** @implements {IPDFStreamReader} */
 class PDFFetchStreamReader {
   constructor(stream) {
     this._stream = stream;
     this._reader = null;
     this._loaded = 0;
     this._filename = null;
-    let source = stream.source;
-    this._withCredentials = source.withCredentials;
+    const source = stream.source;
+    this._withCredentials = source.withCredentials || false;
     this._contentLength = source.length;
     this._headersCapability = createPromiseCapability();
     this._disableRange = source.disableRange || false;
@@ -95,15 +98,15 @@ class PDFFetchStreamReader {
     this._isRangeSupported = !source.disableRange;
 
     this._headers = new Headers();
-    for (let property in this._stream.httpHeaders) {
-      let value = this._stream.httpHeaders[property];
+    for (const property in this._stream.httpHeaders) {
+      const value = this._stream.httpHeaders[property];
       if (typeof value === 'undefined') {
         continue;
       }
       this._headers.append(property, value);
     }
 
-    let url = source.url;
+    const url = source.url;
     fetch(url, createFetchOptions(this._headers, this._withCredentials,
         this._abortController)).then((response) => {
       if (!validateResponseStatus(response.status)) {
@@ -115,7 +118,7 @@ class PDFFetchStreamReader {
       const getResponseHeader = (name) => {
         return response.headers.get(name);
       };
-      let { allowRangeRequests, suggestedLength, } =
+      const { allowRangeRequests, suggestedLength, } =
         validateRangeRequestCapabilities({
           getResponseHeader,
           isHttp: this._stream.isHttp,
@@ -132,7 +135,7 @@ class PDFFetchStreamReader {
       // We need to stop reading when range is supported and streaming is
       // disabled.
       if (!this._isStreamingSupported && this._isRangeSupported) {
-        this.cancel(new AbortException('streaming is disabled'));
+        this.cancel(new AbortException('Streaming is disabled.'));
       }
     }).catch(this._headersCapability.reject);
 
@@ -172,7 +175,7 @@ class PDFFetchStreamReader {
         total: this._contentLength,
       });
     }
-    let buffer = new Uint8Array(value).buffer;
+    const buffer = new Uint8Array(value).buffer;
     return { value: buffer, done: false, };
   }
 
@@ -186,13 +189,14 @@ class PDFFetchStreamReader {
   }
 }
 
+/** @implements {IPDFStreamRangeReader} */
 class PDFFetchStreamRangeReader {
   constructor(stream, begin, end) {
     this._stream = stream;
     this._reader = null;
     this._loaded = 0;
-    let source = stream.source;
-    this._withCredentials = source.withCredentials;
+    const source = stream.source;
+    this._withCredentials = source.withCredentials || false;
     this._readCapability = createPromiseCapability();
     this._isStreamingSupported = !source.disableStream;
 
@@ -201,17 +205,16 @@ class PDFFetchStreamRangeReader {
     }
 
     this._headers = new Headers();
-    for (let property in this._stream.httpHeaders) {
-      let value = this._stream.httpHeaders[property];
+    for (const property in this._stream.httpHeaders) {
+      const value = this._stream.httpHeaders[property];
       if (typeof value === 'undefined') {
         continue;
       }
       this._headers.append(property, value);
     }
+    this._headers.append('Range', `bytes=${begin}-${end - 1}`);
 
-    let rangeStr = begin + '-' + (end - 1);
-    this._headers.append('Range', 'bytes=' + rangeStr);
-    let url = source.url;
+    const url = source.url;
     fetch(url, createFetchOptions(this._headers, this._withCredentials,
         this._abortController)).then((response) => {
       if (!validateResponseStatus(response.status)) {
@@ -238,7 +241,7 @@ class PDFFetchStreamRangeReader {
     if (this.onProgress) {
       this.onProgress({ loaded: this._loaded, });
     }
-    let buffer = new Uint8Array(value).buffer;
+    const buffer = new Uint8Array(value).buffer;
     return { value: buffer, done: false, };
   }
 
diff --git a/src/display/network.js b/src/display/network.js
index 1f2dc8a80..8cc6b693b 100644
--- a/src/display/network.js
+++ b/src/display/network.js
@@ -12,6 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+/* eslint no-var: error */
 
 import { assert, createPromiseCapability, stringToBytes } from '../shared/util';
 import {
@@ -24,71 +25,70 @@ if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
                   'be used with FIREFOX or MOZCENTRAL build.');
 }
 
-var OK_RESPONSE = 200;
-var PARTIAL_CONTENT_RESPONSE = 206;
-
-function NetworkManager(url, args) {
-  this.url = url;
-  args = args || {};
-  this.isHttp = /^https?:/i.test(url);
-  this.httpHeaders = (this.isHttp && args.httpHeaders) || {};
-  this.withCredentials = args.withCredentials || false;
-  this.getXhr = args.getXhr ||
-    function NetworkManager_getXhr() {
-      return new XMLHttpRequest();
-    };
-
-  this.currXhrId = 0;
-  this.pendingRequests = Object.create(null);
-}
+const OK_RESPONSE = 200;
+const PARTIAL_CONTENT_RESPONSE = 206;
 
 function getArrayBuffer(xhr) {
-  var data = xhr.response;
+  const data = xhr.response;
   if (typeof data !== 'string') {
     return data;
   }
-  let array = stringToBytes(data);
+  const array = stringToBytes(data);
   return array.buffer;
 }
 
-NetworkManager.prototype = {
-  requestRange: function NetworkManager_requestRange(begin, end, listeners) {
-    var args = {
+class NetworkManager {
+  constructor(url, args) {
+    this.url = url;
+    args = args || {};
+    this.isHttp = /^https?:/i.test(url);
+    this.httpHeaders = (this.isHttp && args.httpHeaders) || {};
+    this.withCredentials = args.withCredentials || false;
+    this.getXhr = args.getXhr ||
+      function NetworkManager_getXhr() {
+        return new XMLHttpRequest();
+      };
+
+    this.currXhrId = 0;
+    this.pendingRequests = Object.create(null);
+  }
+
+  requestRange(begin, end, listeners) {
+    const args = {
       begin,
       end,
     };
-    for (var prop in listeners) {
+    for (const prop in listeners) {
       args[prop] = listeners[prop];
     }
     return this.request(args);
-  },
+  }
 
-  requestFull: function NetworkManager_requestFull(listeners) {
+  requestFull(listeners) {
     return this.request(listeners);
-  },
+  }
 
-  request: function NetworkManager_request(args) {
-    var xhr = this.getXhr();
-    var xhrId = this.currXhrId++;
-    var pendingRequest = this.pendingRequests[xhrId] = {
+  request(args) {
+    const xhr = this.getXhr();
+    const xhrId = this.currXhrId++;
+    const pendingRequest = this.pendingRequests[xhrId] = {
       xhr,
     };
 
     xhr.open('GET', this.url);
     xhr.withCredentials = this.withCredentials;
-    for (var property in this.httpHeaders) {
-      var value = this.httpHeaders[property];
+    for (const property in this.httpHeaders) {
+      const value = this.httpHeaders[property];
       if (typeof value === 'undefined') {
         continue;
       }
       xhr.setRequestHeader(property, value);
     }
     if (this.isHttp && 'begin' in args && 'end' in args) {
-      var rangeStr = args.begin + '-' + (args.end - 1);
-      xhr.setRequestHeader('Range', 'bytes=' + rangeStr);
-      pendingRequest.expectedStatus = 206;
+      xhr.setRequestHeader('Range', `bytes=${args.begin}-${args.end - 1}`);
+      pendingRequest.expectedStatus = PARTIAL_CONTENT_RESPONSE;
     } else {
-      pendingRequest.expectedStatus = 200;
+      pendingRequest.expectedStatus = OK_RESPONSE;
     }
     xhr.responseType = 'arraybuffer';
 
@@ -108,10 +108,10 @@ NetworkManager.prototype = {
     xhr.send(null);
 
     return xhrId;
-  },
+  }
 
-  onProgress: function NetworkManager_onProgress(xhrId, evt) {
-    var pendingRequest = this.pendingRequests[xhrId];
+  onProgress(xhrId, evt) {
+    const pendingRequest = this.pendingRequests[xhrId];
     if (!pendingRequest) {
       // Maybe abortRequest was called...
       return;
@@ -120,16 +120,16 @@ NetworkManager.prototype = {
     if (pendingRequest.onProgress) {
       pendingRequest.onProgress(evt);
     }
-  },
+  }
 
-  onStateChange: function NetworkManager_onStateChange(xhrId, evt) {
-    var pendingRequest = this.pendingRequests[xhrId];
+  onStateChange(xhrId, evt) {
+    const pendingRequest = this.pendingRequests[xhrId];
     if (!pendingRequest) {
       // Maybe abortRequest was called...
       return;
     }
 
-    var xhr = pendingRequest.xhr;
+    const xhr = pendingRequest.xhr;
     if (xhr.readyState >= 2 && pendingRequest.onHeadersReceived) {
       pendingRequest.onHeadersReceived();
       delete pendingRequest.onHeadersReceived;
@@ -141,27 +141,27 @@ NetworkManager.prototype = {
 
     if (!(xhrId in this.pendingRequests)) {
       // The XHR request might have been aborted in onHeadersReceived()
-      // callback, in which case we should abort request
+      // callback, in which case we should abort request.
       return;
     }
 
     delete this.pendingRequests[xhrId];
 
-    // success status == 0 can be on ftp, file and other protocols
+    // Success status == 0 can be on ftp, file and other protocols.
     if (xhr.status === 0 && this.isHttp) {
       if (pendingRequest.onError) {
         pendingRequest.onError(xhr.status);
       }
       return;
     }
-    var xhrStatus = xhr.status || OK_RESPONSE;
+    const xhrStatus = xhr.status || OK_RESPONSE;
 
     // From http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35.2:
     // "A server MAY ignore the Range header". This means it's possible to
     // get a 200 rather than a 206 response from a range request.
-    var ok_response_on_range_request =
-        xhrStatus === OK_RESPONSE &&
-        pendingRequest.expectedStatus === PARTIAL_CONTENT_RESPONSE;
+    const ok_response_on_range_request =
+      xhrStatus === OK_RESPONSE &&
+      pendingRequest.expectedStatus === PARTIAL_CONTENT_RESPONSE;
 
     if (!ok_response_on_range_request &&
         xhrStatus !== pendingRequest.expectedStatus) {
@@ -171,13 +171,12 @@ NetworkManager.prototype = {
       return;
     }
 
-    var chunk = getArrayBuffer(xhr);
+    const chunk = getArrayBuffer(xhr);
     if (xhrStatus === PARTIAL_CONTENT_RESPONSE) {
-      var rangeHeader = xhr.getResponseHeader('Content-Range');
-      var matches = /bytes (\d+)-(\d+)\/(\d+)/.exec(rangeHeader);
-      var begin = parseInt(matches[1], 10);
+      const rangeHeader = xhr.getResponseHeader('Content-Range');
+      const matches = /bytes (\d+)-(\d+)\/(\d+)/.exec(rangeHeader);
       pendingRequest.onDone({
-        begin,
+        begin: parseInt(matches[1], 10),
         chunk,
       });
     } else if (chunk) {
@@ -188,125 +187,123 @@ NetworkManager.prototype = {
     } else if (pendingRequest.onError) {
       pendingRequest.onError(xhr.status);
     }
-  },
+  }
 
-  hasPendingRequests: function NetworkManager_hasPendingRequests() {
-    for (var xhrId in this.pendingRequests) {
+  hasPendingRequests() {
+    for (const xhrId in this.pendingRequests) {
       return true;
     }
     return false;
-  },
+  }
 
-  getRequestXhr: function NetworkManager_getXhr(xhrId) {
+  getRequestXhr(xhrId) {
     return this.pendingRequests[xhrId].xhr;
-  },
+  }
 
-  isPendingRequest: function NetworkManager_isPendingRequest(xhrId) {
+  isPendingRequest(xhrId) {
     return xhrId in this.pendingRequests;
-  },
+  }
 
-  abortAllRequests: function NetworkManager_abortAllRequests() {
-    for (var xhrId in this.pendingRequests) {
+  abortAllRequests() {
+    for (const xhrId in this.pendingRequests) {
       this.abortRequest(xhrId | 0);
     }
-  },
+  }
 
-  abortRequest: function NetworkManager_abortRequest(xhrId) {
-    var xhr = this.pendingRequests[xhrId].xhr;
+  abortRequest(xhrId) {
+    const xhr = this.pendingRequests[xhrId].xhr;
     delete this.pendingRequests[xhrId];
     xhr.abort();
-  },
-};
-
-/** @implements {IPDFStream} */
-function PDFNetworkStream(source) {
-  this._source = source;
-  this._manager = new NetworkManager(source.url, {
-    httpHeaders: source.httpHeaders,
-    withCredentials: source.withCredentials,
-  });
-  this._rangeChunkSize = source.rangeChunkSize;
-  this._fullRequestReader = null;
-  this._rangeRequestReaders = [];
+  }
 }
 
-PDFNetworkStream.prototype = {
-  _onRangeRequestReaderClosed:
-      function PDFNetworkStream_onRangeRequestReaderClosed(reader) {
-    var i = this._rangeRequestReaders.indexOf(reader);
+/** @implements {IPDFStream} */
+class PDFNetworkStream {
+  constructor(source) {
+    this._source = source;
+    this._manager = new NetworkManager(source.url, {
+      httpHeaders: source.httpHeaders,
+      withCredentials: source.withCredentials,
+    });
+    this._rangeChunkSize = source.rangeChunkSize;
+    this._fullRequestReader = null;
+    this._rangeRequestReaders = [];
+  }
+
+  _onRangeRequestReaderClosed(reader) {
+    const i = this._rangeRequestReaders.indexOf(reader);
     if (i >= 0) {
       this._rangeRequestReaders.splice(i, 1);
     }
-  },
+  }
 
-  getFullReader: function PDFNetworkStream_getFullReader() {
+  getFullReader() {
     assert(!this._fullRequestReader);
     this._fullRequestReader =
       new PDFNetworkStreamFullRequestReader(this._manager, this._source);
     return this._fullRequestReader;
-  },
+  }
 
-  getRangeReader: function PDFNetworkStream_getRangeReader(begin, end) {
-    var reader = new PDFNetworkStreamRangeRequestReader(this._manager,
-                                                        begin, end);
+  getRangeReader(begin, end) {
+    const reader = new PDFNetworkStreamRangeRequestReader(this._manager,
+                                                          begin, end);
     reader.onClosed = this._onRangeRequestReaderClosed.bind(this);
     this._rangeRequestReaders.push(reader);
     return reader;
-  },
+  }
 
-  cancelAllRequests: function PDFNetworkStream_cancelAllRequests(reason) {
+  cancelAllRequests(reason) {
     if (this._fullRequestReader) {
       this._fullRequestReader.cancel(reason);
     }
-    var readers = this._rangeRequestReaders.slice(0);
-    readers.forEach(function (reader) {
+    const readers = this._rangeRequestReaders.slice(0);
+    readers.forEach(function(reader) {
       reader.cancel(reason);
     });
-  },
-};
-
-/** @implements {IPDFStreamReader} */
-function PDFNetworkStreamFullRequestReader(manager, source) {
-  this._manager = manager;
-
-  var args = {
-    onHeadersReceived: this._onHeadersReceived.bind(this),
-    onDone: this._onDone.bind(this),
-    onError: this._onError.bind(this),
-    onProgress: this._onProgress.bind(this),
-  };
-  this._url = source.url;
-  this._fullRequestId = manager.requestFull(args);
-  this._headersReceivedCapability = createPromiseCapability();
-  this._disableRange = source.disableRange || false;
-  this._contentLength = source.length; // optional
-  this._rangeChunkSize = source.rangeChunkSize;
-  if (!this._rangeChunkSize && !this._disableRange) {
-    this._disableRange = true;
   }
-
-  this._isStreamingSupported = false;
-  this._isRangeSupported = false;
-
-  this._cachedChunks = [];
-  this._requests = [];
-  this._done = false;
-  this._storedError = undefined;
-  this._filename = null;
-
-  this.onProgress = null;
 }
 
-PDFNetworkStreamFullRequestReader.prototype = {
-  _onHeadersReceived:
-      function PDFNetworkStreamFullRequestReader_onHeadersReceived() {
-    var fullRequestXhrId = this._fullRequestId;
-    var fullRequestXhr = this._manager.getRequestXhr(fullRequestXhrId);
+/** @implements {IPDFStreamReader} */
+class PDFNetworkStreamFullRequestReader {
+  constructor(manager, source) {
+    this._manager = manager;
+
+    const args = {
+      onHeadersReceived: this._onHeadersReceived.bind(this),
+      onDone: this._onDone.bind(this),
+      onError: this._onError.bind(this),
+      onProgress: this._onProgress.bind(this),
+    };
+    this._url = source.url;
+    this._fullRequestId = manager.requestFull(args);
+    this._headersReceivedCapability = createPromiseCapability();
+    this._disableRange = source.disableRange || false;
+    this._contentLength = source.length; // Optional
+    this._rangeChunkSize = source.rangeChunkSize;
+    if (!this._rangeChunkSize && !this._disableRange) {
+      this._disableRange = true;
+    }
+
+    this._isStreamingSupported = false;
+    this._isRangeSupported = false;
+
+    this._cachedChunks = [];
+    this._requests = [];
+    this._done = false;
+    this._storedError = undefined;
+    this._filename = null;
+
+    this.onProgress = null;
+  }
+
+  _onHeadersReceived() {
+    const fullRequestXhrId = this._fullRequestId;
+    const fullRequestXhr = this._manager.getRequestXhr(fullRequestXhrId);
 
     const getResponseHeader = (name) => {
       return fullRequestXhr.getResponseHeader(name);
     };
-    let { allowRangeRequests, suggestedLength, } =
+    const { allowRangeRequests, suggestedLength, } =
       validateRangeRequestCapabilities({
         getResponseHeader,
         isHttp: this._manager.isHttp,
@@ -331,12 +328,12 @@ PDFNetworkStreamFullRequestReader.prototype = {
     }
 
     this._headersReceivedCapability.resolve();
-  },
+  }
 
-  _onDone: function PDFNetworkStreamFullRequestReader_onDone(args) {
+  _onDone(args) {
     if (args) {
       if (this._requests.length > 0) {
-        var requestCapability = this._requests.shift();
+        const requestCapability = this._requests.shift();
         requestCapability.resolve({ value: args.chunk, done: false, });
       } else {
         this._cachedChunks.push(args.chunk);
@@ -346,70 +343,70 @@ PDFNetworkStreamFullRequestReader.prototype = {
     if (this._cachedChunks.length > 0) {
       return;
     }
-    this._requests.forEach(function (requestCapability) {
+    this._requests.forEach(function(requestCapability) {
       requestCapability.resolve({ value: undefined, done: true, });
     });
     this._requests = [];
-  },
+  }
 
-  _onError: function PDFNetworkStreamFullRequestReader_onError(status) {
-    var url = this._url;
-    var exception = createResponseStatusError(status, url);
+  _onError(status) {
+    const url = this._url;
+    const exception = createResponseStatusError(status, url);
     this._storedError = exception;
     this._headersReceivedCapability.reject(exception);
-    this._requests.forEach(function (requestCapability) {
+    this._requests.forEach(function(requestCapability) {
       requestCapability.reject(exception);
     });
     this._requests = [];
     this._cachedChunks = [];
-  },
+  }
 
-  _onProgress: function PDFNetworkStreamFullRequestReader_onProgress(data) {
+  _onProgress(data) {
     if (this.onProgress) {
       this.onProgress({
         loaded: data.loaded,
         total: data.lengthComputable ? data.total : this._contentLength,
       });
     }
-  },
+  }
 
   get filename() {
     return this._filename;
-  },
+  }
 
   get isRangeSupported() {
     return this._isRangeSupported;
-  },
+  }
 
   get isStreamingSupported() {
     return this._isStreamingSupported;
-  },
+  }
 
   get contentLength() {
     return this._contentLength;
-  },
+  }
 
   get headersReady() {
     return this._headersReceivedCapability.promise;
-  },
+  }
 
   async read() {
     if (this._storedError) {
       throw this._storedError;
     }
     if (this._cachedChunks.length > 0) {
-      var chunk = this._cachedChunks.shift();
+      const chunk = this._cachedChunks.shift();
       return { value: chunk, done: false, };
     }
     if (this._done) {
       return { value: undefined, done: true, };
     }
-    var requestCapability = createPromiseCapability();
+    const requestCapability = createPromiseCapability();
     this._requests.push(requestCapability);
     return requestCapability.promise;
-  },
+  }
 
-  cancel: function PDFNetworkStreamFullRequestReader_cancel(reason) {
+  cancel(reason) {
     this._done = true;
     this._headersReceivedCapability.reject(reason);
     this._requests.forEach(function (requestCapability) {
@@ -420,75 +417,75 @@ PDFNetworkStreamFullRequestReader.prototype = {
       this._manager.abortRequest(this._fullRequestId);
     }
     this._fullRequestReader = null;
-  },
-};
-
-/** @implements {IPDFStreamRangeReader} */
-function PDFNetworkStreamRangeRequestReader(manager, begin, end) {
-  this._manager = manager;
-  var args = {
-    onDone: this._onDone.bind(this),
-    onProgress: this._onProgress.bind(this),
-  };
-  this._requestId = manager.requestRange(begin, end, args);
-  this._requests = [];
-  this._queuedChunk = null;
-  this._done = false;
-
-  this.onProgress = null;
-  this.onClosed = null;
+  }
 }
 
-PDFNetworkStreamRangeRequestReader.prototype = {
-  _close: function PDFNetworkStreamRangeRequestReader_close() {
+/** @implements {IPDFStreamRangeReader} */
+class PDFNetworkStreamRangeRequestReader {
+  constructor(manager, begin, end) {
+    this._manager = manager;
+    const args = {
+      onDone: this._onDone.bind(this),
+      onProgress: this._onProgress.bind(this),
+    };
+    this._requestId = manager.requestRange(begin, end, args);
+    this._requests = [];
+    this._queuedChunk = null;
+    this._done = false;
+
+    this.onProgress = null;
+    this.onClosed = null;
+  }
+
+  _close() {
     if (this.onClosed) {
       this.onClosed(this);
     }
-  },
+  }
 
-  _onDone: function PDFNetworkStreamRangeRequestReader_onDone(data) {
-    var chunk = data.chunk;
+  _onDone(data) {
+    const chunk = data.chunk;
     if (this._requests.length > 0) {
-      var requestCapability = this._requests.shift();
+      const requestCapability = this._requests.shift();
       requestCapability.resolve({ value: chunk, done: false, });
     } else {
       this._queuedChunk = chunk;
     }
     this._done = true;
-    this._requests.forEach(function (requestCapability) {
+    this._requests.forEach(function(requestCapability) {
       requestCapability.resolve({ value: undefined, done: true, });
     });
     this._requests = [];
     this._close();
-  },
+  }
 
-  _onProgress: function PDFNetworkStreamRangeRequestReader_onProgress(evt) {
+  _onProgress(evt) {
     if (!this.isStreamingSupported && this.onProgress) {
       this.onProgress({
         loaded: evt.loaded,
       });
     }
-  },
+  }
 
   get isStreamingSupported() {
-    return false; // TODO allow progressive range bytes loading
-  },
+    return false;
+  }
 
   async read() {
     if (this._queuedChunk !== null) {
-      var chunk = this._queuedChunk;
+      const chunk = this._queuedChunk;
       this._queuedChunk = null;
       return { value: chunk, done: false, };
     }
     if (this._done) {
       return { value: undefined, done: true, };
     }
-    var requestCapability = createPromiseCapability();
+    const requestCapability = createPromiseCapability();
     this._requests.push(requestCapability);
     return requestCapability.promise;
-  },
+  }
 
-  cancel: function PDFNetworkStreamRangeRequestReader_cancel(reason) {
+  cancel(reason) {
     this._done = true;
     this._requests.forEach(function (requestCapability) {
       requestCapability.resolve({ value: undefined, done: true, });
@@ -498,10 +495,9 @@ PDFNetworkStreamRangeRequestReader.prototype = {
       this._manager.abortRequest(this._requestId);
     }
     this._close();
-  },
-};
+  }
+}
 
 export {
   PDFNetworkStream,
-  NetworkManager,
 };
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,