perf: Use Map.getOrInsert/getOrInsertComputed native methods (#9546)

Added polyfills for `Map.getOrInsert()` and
`Map.getOrInsertComputed()` from the TC39 upsert proposal and refactor
the codebase to use them.
These methods replace the common "check if key exists, then set default"
pattern with a single atomic operation. This improves code readability
and eliminates redundant map lookups throughout the player.

---------

Co-authored-by: Álvaro Velad Galván <ladvan91@hotmail.com>

build/types/polyfill

@@ -3,6 +3,7 @@
 +../../lib/polyfill/eme_encryption_scheme.js
 +../../lib/polyfill/encryption_scheme_media_key_system_access.js
 +../../lib/polyfill/encryption_scheme_utils.js
++../../lib/polyfill/map.js
 +../../lib/polyfill/mcap_encryption_scheme.js
 +../../lib/polyfill/mediasource.js
 +../../lib/polyfill/media_capabilities.js

externs/map.js

@@ -0,0 +1,59 @@
+/*! @license
+ * Shaka Player
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @fileoverview Externs for Map getOrInsert/getOrInsertComputed methods
+ *
+ * @externs
+ */
+
+/**
+ * Returns the value for the given key if present; otherwise inserts
+ * the default value, and returns that.
+ * @param {K} key
+ * @param {V} defaultValue
+ * @return {V}
+ * @this {Map<K, V>}
+ * @template K, V
+ */
+// eslint-disable-next-line no-extend-native
+Map.prototype.getOrInsert = function(key, defaultValue) {};
+
+/**
+ * Returns the value for the given key if present; otherwise calls
+ * the callback with the key, inserts the returned value, and returns that.
+ * @param {K} key
+ * @param {function(K): V} callbackFunction
+ * @return {V}
+ * @this {Map<K, V>}
+ * @template K, V
+ */
+// eslint-disable-next-line no-extend-native
+Map.prototype.getOrInsertComputed = function(key, callbackFunction) {};
+
+/**
+ * Returns the value for the given key if present; otherwise inserts
+ * the default value, and returns that.
+ * @param {K} key
+ * @param {V} defaultValue
+ * @return {V}
+ * @this {WeakMap<K, V>}
+ * @template K, V
+ */
+// eslint-disable-next-line no-extend-native
+WeakMap.prototype.getOrInsert = function(key, defaultValue) {};
+
+/**
+ * Returns the value for the given key if present; otherwise calls
+ * the callback with the key, inserts the returned value, and returns that.
+ * @param {K} key
+ * @param {function(K): V} callbackFunction
+ * @return {V}
+ * @this {WeakMap<K, V>}
+ * @template K, V
+ */
+// eslint-disable-next-line no-extend-native
+WeakMap.prototype.getOrInsertComputed = function(key, callbackFunction) {};

lib/ads/svta_ad_manager.js

@@ -258,8 +258,7 @@ shaka.ads.SvtaAdManager = class {
     let cuepointsChanged = false;
     for (const tracking of trackings) {
       const id = JSON.stringify(tracking);
-      if (!this.trackings_.has(id)) {
-        this.trackings_.set(id, tracking);
+      if (this.trackings_.getOrInsert(id, tracking) === tracking) {
         cuepointsChanged = true;
       }
     }

lib/cea/cea_decoder.js

@@ -359,11 +359,9 @@ shaka.cea.CeaDecoder = class {
         if (serviceNumber != 0) {
           this.streams_.add('svc'+ serviceNumber);
           // If the service doesn't already exist, create it.
-          if (!this.serviceNumberToService_.has(serviceNumber)) {
-            const service = new shaka.cea.Cea708Service(serviceNumber);
-            this.serviceNumberToService_.set(serviceNumber, service);
-          }
-          const service = this.serviceNumberToService_.get(serviceNumber);
+          const service = this.serviceNumberToService_.getOrInsertComputed(
+              serviceNumber,
+              (num) => new shaka.cea.Cea708Service(num));
 
           // Process all control codes.
           const startPos = dtvccPacket.getPosition();

lib/dash/content_protection.js

@@ -543,13 +543,12 @@ shaka.dash.ContentProtection = class {
     try {
       // Try parsing PSSH data.
       init = psshs.map((pssh) => {
-        if (!this.psshToInitData_.has(pssh)) {
-          const initData = shaka.util.Uint8ArrayUtils.fromBase64(pssh);
-          this.psshToInitData_.set(pssh, initData);
-        }
+        const initData = this.psshToInitData_.getOrInsertComputed(pssh, () => {
+          return shaka.util.Uint8ArrayUtils.fromBase64(pssh);
+        });
         return {
           initDataType: 'cenc',
-          initData: this.psshToInitData_.get(pssh),
+          initData,
           keyId: null,
         };
       });

lib/dash/dash_parser.js

@@ -2555,11 +2555,9 @@ shaka.dash.DashParser = class {
 
     if (contextId && context.dynamic && !this.streamMap_.has(contextId)) {
       const periodId = context.period.id || '';
-      if (!this.indexStreamMap_.has(periodId)) {
-        this.indexStreamMap_.set(periodId, []);
-      }
       this.streamMap_.set(contextId, stream);
-      this.indexStreamMap_.get(periodId).push(contextId);
+      this.indexStreamMap_.getOrInsertComputed(periodId, () => [])
+          .push(contextId);
     }
 
     return stream;

lib/drm/drm_engine.js

@@ -1099,10 +1099,8 @@ shaka.drm.DrmEngine = class {
       // Get all the key systems in the variant that shouldHaveLicenseServer.
       const drmInfos = this.getVariantDrmInfos_(variant);
       for (const info of drmInfos) {
-        if (!drmInfosByKeySystem.has(info.keySystem)) {
-          drmInfosByKeySystem.set(info.keySystem, []);
-        }
-        drmInfosByKeySystem.get(info.keySystem).push(info);
+        drmInfosByKeySystem.getOrInsertComputed(info.keySystem, () => [])
+            .push(info);
       }
     }
 

lib/hls/hls_parser.js

@@ -1311,9 +1311,7 @@ shaka.hls.HlsParser = class {
       const value = variableTag.getAttributeValue('VALUE');
       const queryParam = variableTag.getAttributeValue('QUERYPARAM');
       if (name && value) {
-        if (!this.globalVariables_.has(name)) {
-          this.globalVariables_.set(name, value);
-        }
+        this.globalVariables_.getOrInsert(name, value);
       }
       if (queryParam) {
         const queryParamValue = queryParams.get(queryParam)[0];
@@ -1340,9 +1338,7 @@ shaka.hls.HlsParser = class {
       const queryParam = variableTag.getAttributeValue('QUERYPARAM');
       const mediaImport = variableTag.getAttributeValue('IMPORT');
       if (name && value) {
-        if (!mediaVariables.has(name)) {
-          mediaVariables.set(name, value);
-        }
+        mediaVariables.getOrInsert(name, value);
       }
       if (queryParam) {
         const queryParamValue = queryParams.get(queryParam)[0];
@@ -1652,10 +1648,8 @@ shaka.hls.HlsParser = class {
         } else if ((i + 1) < chapterList.length) {
           item.endTime = chapterList[i + 1]['start-time'];
         }
-        if (!chapterByLanguage.has(title.language)) {
-          chapterByLanguage.set(title.language, []);
-        }
-        chapterByLanguage.get(title.language).push(item);
+        chapterByLanguage.getOrInsertComputed(title.language, () => [])
+            .push(item);
       }
     }
 
@@ -1801,14 +1795,12 @@ shaka.hls.HlsParser = class {
           const keyUris = shaka.hls.Utils.constructSegmentUris(
               getUris(), drmTag.getRequiredAttrValue('URI'), variables);
           const keyMapKey = keyUris.sort().join('');
-          if (!this.aesKeyMap_.has(keyMapKey)) {
+          this.aesKeyMap_.getOrInsertComputed(keyMapKey, () => {
             const requestType = shaka.net.NetworkingEngine.RequestType.KEY;
             const request = shaka.net.NetworkingEngine.makeRequest(
                 keyUris, this.config_.retryParameters);
-            const keyResponse = this.makeNetworkRequest_(request, requestType)
-                .promise;
-            this.aesKeyMap_.set(keyMapKey, keyResponse);
-          }
+            return this.makeNetworkRequest_(request, requestType).promise;
+          });
           continue;
         } else if (keyFormat == 'identity') {
           // eslint-disable-next-line no-await-in-loop
@@ -3581,7 +3573,7 @@ shaka.hls.HlsParser = class {
     const keyMapKey = keyUris.sort().join('');
     const aesKeyInfoKey =
         `${drmTag.toString()}-${firstMediaSequenceNumber}-${keyMapKey}`;
-    if (!this.aesKeyInfoMap_.has(aesKeyInfoKey)) {
+    return this.aesKeyInfoMap_.getOrInsertComputed(aesKeyInfoKey, () => {
       // Default AES-128
       const keyInfo = {
         bitsKey: 128,
@@ -3604,15 +3596,13 @@ shaka.hls.HlsParser = class {
       // Don't download the key object until the segment is parsed, to avoid a
       // startup delay for long manifests with lots of keys.
       keyInfo.fetchKey = async () => {
-        if (!this.aesKeyMap_.has(keyMapKey)) {
-          const requestType = shaka.net.NetworkingEngine.RequestType.KEY;
-          const request = shaka.net.NetworkingEngine.makeRequest(
-              keyUris, this.config_.retryParameters);
-          const keyResponse = this.makeNetworkRequest_(request, requestType)
-              .promise;
-          this.aesKeyMap_.set(keyMapKey, keyResponse);
-        }
-        const keyResponse = await this.aesKeyMap_.get(keyMapKey);
+        const keyResponse = await this.aesKeyMap_.getOrInsertComputed(
+            keyMapKey, () => {
+              const requestType = shaka.net.NetworkingEngine.RequestType.KEY;
+              const request = shaka.net.NetworkingEngine.makeRequest(
+                  keyUris, this.config_.retryParameters);
+              return this.makeNetworkRequest_(request, requestType).promise;
+            });
 
         // keyResponse.status is undefined when URI is "data:text/plain;base64,"
         if (!keyResponse.data ||
@@ -3631,9 +3621,8 @@ shaka.hls.HlsParser = class {
             'raw', keyResponse.data, algorithm, true, ['decrypt']);
         keyInfo.fetchKey = undefined; // No longer needed.
       };
-      this.aesKeyInfoMap_.set(aesKeyInfoKey, keyInfo);
-    }
-    return this.aesKeyInfoMap_.get(aesKeyInfoKey);
+      return keyInfo;
+    });
   }
 
 
@@ -3843,30 +3832,31 @@ shaka.hls.HlsParser = class {
       absoluteInitSegmentUris.toString(),
       mapTag.getAttributeValue('BYTERANGE', ''),
     ].join('-');
-    if (!this.mapTagToInitSegmentRefMap_.has(mapTagKey)) {
-      /** @type {shaka.extern.aesKey|undefined} */
-      let aesKey = undefined;
-      let byteRangeTag = null;
-      let encrypted = false;
-      for (const tag of tags) {
-        if (tag.name == 'EXT-X-KEY') {
-          const method = tag.getRequiredAttrValue('METHOD');
-          if (this.isAesMethod_(method) && tag.id < mapTag.id) {
-            encrypted = false;
-            aesKey =
-                this.parseAESDrmTag_(tag, playlist, getUris, variables);
-          } else {
-            encrypted = method != 'NONE';
+    return this.mapTagToInitSegmentRefMap_.getOrInsertComputed(
+        mapTagKey, () => {
+          goog.asserts.assert(mapTag, 'mapTag should be non-null');
+          /** @type {shaka.extern.aesKey|undefined} */
+          let aesKey = undefined;
+          /** @type {shaka.hls.Tag|undefined} */
+          let byteRangeTag = undefined;
+          let encrypted = false;
+          for (const tag of tags) {
+            if (tag.name == 'EXT-X-KEY') {
+              const method = tag.getRequiredAttrValue('METHOD');
+              if (this.isAesMethod_(method) && tag.id < mapTag.id) {
+                encrypted = false;
+                aesKey =
+                    this.parseAESDrmTag_(tag, playlist, getUris, variables);
+              } else {
+                encrypted = method != 'NONE';
+              }
+            } else if (tag.name == 'EXT-X-BYTERANGE' && tag.id < mapTag.id) {
+              byteRangeTag = tag;
+            }
           }
-        } else if (tag.name == 'EXT-X-BYTERANGE' && tag.id < mapTag.id) {
-          byteRangeTag = tag;
-        }
-      }
-      const initSegmentRef = this.createInitSegmentReference_(
-          absoluteInitSegmentUris, mapTag, byteRangeTag, aesKey, encrypted);
-      this.mapTagToInitSegmentRefMap_.set(mapTagKey, initSegmentRef);
-    }
-    return this.mapTagToInitSegmentRefMap_.get(mapTagKey);
+          return this.createInitSegmentReference_(
+              absoluteInitSegmentUris, mapTag, byteRangeTag, aesKey, encrypted);
+        });
   }
 
   /**
@@ -5224,16 +5214,15 @@ shaka.hls.HlsParser = class {
     const parsedData = shaka.net.DataUriPlugin.parseRaw(uri.split('?')[0]);
 
     const psshKey = uri.split('?')[0];
-    if (!this.psshToInitData_.has(psshKey)) {
+    const initData = this.psshToInitData_.getOrInsertComputed(psshKey, () => {
       // The data encoded in the URI is a PSSH box to be used as init data.
-      const initData = shaka.util.BufferUtils.toUint8(parsedData.data);
-      this.psshToInitData_.set(psshKey, initData);
-    }
+      return shaka.util.BufferUtils.toUint8(parsedData.data);
+    });
     const drmInfo = shaka.util.ManifestParserUtils.createDrmInfo(
         'com.widevine.alpha',
         encryptionScheme,
         /* initData= */ [
-          {initDataType: 'cenc', initData: this.psshToInitData_.get(psshKey)},
+          {initDataType: 'cenc', initData},
         ],
         /* keySystemUri= */ undefined,
         /* mediaTypeList= */ parsedData.typeInfoList);
@@ -5333,16 +5322,15 @@ shaka.hls.HlsParser = class {
     const parsedData = shaka.net.DataUriPlugin.parseRaw(uri.split('?')[0]);
 
     const psshKey = uri.split('?')[0];
-    if (!this.psshToInitData_.has(psshKey)) {
+    const initData = this.psshToInitData_.getOrInsertComputed(psshKey, () => {
       // The data encoded in the URI is a PSSH box to be used as init data.
-      const initData = shaka.util.BufferUtils.toUint8(parsedData.data);
-      this.psshToInitData_.set(psshKey, initData);
-    }
+      return shaka.util.BufferUtils.toUint8(parsedData.data);
+    });
     const drmInfo = shaka.util.ManifestParserUtils.createDrmInfo(
         /* keySystem= */ 'com.huawei.wiseplay',
         encryptionScheme,
         /* initData= */ [
-          {initDataType: 'cenc', initData: this.psshToInitData_.get(psshKey)},
+          {initDataType: 'cenc', initData},
         ],
         /* keySystemUri= */ undefined,
         /* mediaTypeList= */ parsedData.typeInfoList);
@@ -5405,15 +5393,13 @@ shaka.hls.HlsParser = class {
               keyUris[0].split('data:text/plain;base64,').pop()));
     } else {
       const keyMapKey = keyUris.sort().join('');
-      if (!this.identityKeyMap_.has(keyMapKey)) {
-        const requestType = shaka.net.NetworkingEngine.RequestType.KEY;
-        const request = shaka.net.NetworkingEngine.makeRequest(
-            keyUris, this.config_.retryParameters);
-        const keyResponse = this.makeNetworkRequest_(request, requestType)
-            .promise;
-        this.identityKeyMap_.set(keyMapKey, keyResponse);
-      }
-      const keyResponse = await this.identityKeyMap_.get(keyMapKey);
+      const keyResponse = await this.identityKeyMap_.getOrInsertComputed(
+          keyMapKey, () => {
+            const requestType = shaka.net.NetworkingEngine.RequestType.KEY;
+            const request = shaka.net.NetworkingEngine.makeRequest(
+                keyUris, this.config_.retryParameters);
+            return this.makeNetworkRequest_(request, requestType).promise;
+          });
       key = shaka.util.Uint8ArrayUtils.toHex(keyResponse.data);
     }
 

lib/media/media_source_capabilities.js

@@ -20,16 +20,10 @@ shaka.media.Capabilities = class {
    */
   static isTypeSupported(type) {
     const supportMap = shaka.media.Capabilities.MediaSourceTypeSupportMap;
-    if (supportMap.has(type)) {
-      return supportMap.get(type);
-    }
-    const mediaSource = window.ManagedMediaSource || window.MediaSource;
-    if (mediaSource) {
-      const currentSupport = mediaSource.isTypeSupported(type);
-      supportMap.set(type, currentSupport);
-      return currentSupport;
-    }
-    return false;
+    return supportMap.getOrInsertComputed(type, () => {
+      const mediaSource = window.ManagedMediaSource || window.MediaSource;
+      return mediaSource?.isTypeSupported(type) ?? false;
+    });
   }
 
   /**

lib/media/media_source_engine.js

@@ -941,10 +941,8 @@ shaka.media.MediaSourceEngine = class {
       }
     } else if (!mimeType.includes('/mp4') && !mimeType.includes('/webm') &&
         shaka.util.TsParser.probe(uint8ArrayData)) {
-      if (!this.tsParsers_.has(contentType)) {
-        this.tsParsers_.set(contentType, new shaka.util.TsParser());
-      }
-      const tsParser = this.tsParsers_.get(contentType);
+      const tsParser = this.tsParsers_.getOrInsertComputed(
+          contentType, () => new shaka.util.TsParser());
       tsParser.clearData();
       tsParser.setDiscontinuitySequence(reference.discontinuitySequence);
       tsParser.parse(uint8ArrayData);

lib/media/streaming_engine.js

@@ -685,17 +685,15 @@ shaka.media.StreamingEngine = class {
         if (mediaState.performingUpdate) {
           const oldStreamTag =
               shaka.media.StreamingEngine.logPrefix_(mediaState);
-          if (!this.deferredCloseSegmentIndex_.has(oldStreamTag)) {
-            // The ongoing update is still using the old stream's segment
-            // reference information.
-            // If we close the old stream now, the update will not complete
-            // correctly.
-            // The next onUpdate_() for this content type will resume the
-            // closeSegmentIndex() operation for the old stream once the ongoing
-            // update has finished, then immediately create a new segment index.
-            this.deferredCloseSegmentIndex_.set(
-                oldStreamTag, mediaState.stream.closeSegmentIndex);
-          }
+          // The ongoing update is still using the old stream's segment
+          // reference information.
+          // If we close the old stream now, the update will not complete
+          // correctly.
+          // The next onUpdate_() for this content type will resume the
+          // closeSegmentIndex() operation for the old stream once the ongoing
+          // update has finished, then immediately create a new segment index.
+          this.deferredCloseSegmentIndex_.getOrInsert(
+              oldStreamTag, mediaState.stream.closeSegmentIndex);
         } else {
           mediaState.stream.closeSegmentIndex();
         }
@@ -1117,8 +1115,8 @@ shaka.media.StreamingEngine = class {
       const stream = streamsByType.get(type);
       if (!this.mediaStates_.has(type)) {
         const mediaState = this.createMediaState_(stream);
-        if (segmentPrefetchById.has(stream.id)) {
-          const segmentPrefetch = segmentPrefetchById.get(stream.id);
+        const segmentPrefetch = segmentPrefetchById.get(stream.id);
+        if (segmentPrefetch) {
           segmentPrefetch.replaceFetchDispatcher(
               (reference, stream, streamDataCallback) => {
                 return this.dispatchFetch_(

lib/polyfill/map.js

@@ -0,0 +1,95 @@
+/*! @license
+ * Shaka Player
+ * Copyright 2016 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+goog.provide('shaka.polyfill.Map');
+
+goog.require('shaka.log');
+goog.require('shaka.polyfill');
+
+/**
+ * @summary A polyfill to provide Map.prototype.getOrInsert,
+ * Map.prototype.getOrInsertComputed, WeakMap.prototype.getOrInsert,
+ * and WeakMap.prototype.getOrInsertComputed methods.
+ * @see https://github.com/tc39/proposal-upsert
+ * @export
+ */
+shaka.polyfill.Map = class {
+  /**
+   * Install the polyfill if needed.
+   * @export
+   */
+  static install() {
+    shaka.log.debug('Map.install');
+
+    // eslint-disable-next-line no-restricted-syntax
+    if (!('getOrInsert' in Map.prototype)) {
+      shaka.log.debug('Map: Installing getOrInsert polyfill.');
+      // eslint-disable-next-line no-extend-native, no-restricted-syntax
+      Map.prototype.getOrInsert = shaka.polyfill.Map.mapGetOrInsert_;
+    }
+
+    // eslint-disable-next-line no-restricted-syntax
+    if (!('getOrInsertComputed' in Map.prototype)) {
+      shaka.log.debug('Map: Installing getOrInsertComputed polyfill.');
+      // eslint-disable-next-line no-extend-native, no-restricted-syntax
+      Map.prototype.getOrInsertComputed =
+        shaka.polyfill.Map.mapGetOrInsertComputed_;
+    }
+
+    shaka.log.debug('WeakMap.install');
+
+    // eslint-disable-next-line no-restricted-syntax
+    if (!('getOrInsert' in WeakMap.prototype)) {
+      shaka.log.debug('WeakMap: Installing getOrInsert polyfill.');
+      // eslint-disable-next-line no-extend-native, no-restricted-syntax
+      WeakMap.prototype.getOrInsert = shaka.polyfill.Map.mapGetOrInsert_;
+    }
+
+    // eslint-disable-next-line no-restricted-syntax
+    if (!('getOrInsertComputed' in WeakMap.prototype)) {
+      shaka.log.debug('WeakMap: Installing getOrInsertComputed polyfill.');
+      // eslint-disable-next-line no-extend-native, no-restricted-syntax
+      WeakMap.prototype.getOrInsertComputed =
+        shaka.polyfill.Map.mapGetOrInsertComputed_;
+    }
+  }
+
+  /**
+   * Returns the value for the given key if present; otherwise inserts
+   * the default value, and returns that.
+   * @param {K} key
+   * @param {V} defaultValue
+   * @return {V}
+   * @this {Map<K, V>|WeakMap<K, V>}
+   * @template K, V
+   * @private
+   */
+  static mapGetOrInsert_(key, defaultValue) {
+    if (!this.has(key)) {
+      this.set(key, defaultValue);
+    }
+    return this.get(key);
+  }
+
+  /**
+   * Returns the value for the given key if present; otherwise calls
+   * the callback with the key, inserts the returned value, and returns that.
+   * @param {K} key
+   * @param {function(K): V} callbackFunction
+   * @return {V}
+   * @this {Map<K, V>|WeakMap<K, V>}
+   * @template K, V
+   * @private
+   */
+  static mapGetOrInsertComputed_(key, callbackFunction) {
+    if (!this.has(key)) {
+      this.set(key, callbackFunction(key));
+    }
+    return this.get(key);
+  }
+};
+
+shaka.polyfill.register(shaka.polyfill.Map.install);

lib/text/speech_to_text.js

@@ -473,23 +473,28 @@ shaka.text.SpeechToText = class {
     if (!mediaElement) {
       return null;
     }
-    if (!shaka.text.SpeechToText.audioObjectMap_.has(mediaElement)) {
-      const AudioContext = window.AudioContext || window.webkitAudioContext;
-      const audioContext = new AudioContext();
-      const sourceNode = audioContext.createMediaElementSource(mediaElement);
-      const destinationNode = audioContext.createMediaStreamDestination();
-      sourceNode.connect(destinationNode);
-      sourceNode.connect(audioContext.destination);
-      const audioTrack = destinationNode.stream.getAudioTracks()[0];
-      shaka.text.SpeechToText.audioObjectMap_.set(mediaElement, {
-        audioContext,
-        sourceNode,
-        destinationNode,
-        audioTrack,
-      });
-    }
     const audioObject =
-        shaka.text.SpeechToText.audioObjectMap_.get(mediaElement);
+        shaka.text.SpeechToText.audioObjectMap_.getOrInsertComputed(
+            mediaElement,
+            () => {
+              const AudioContext =
+                  window.AudioContext || window.webkitAudioContext;
+              const audioContext = new AudioContext();
+              goog.asserts.assert(mediaElement, 'MediaElement should be null');
+              const sourceNode =
+                  audioContext.createMediaElementSource(mediaElement);
+              const destinationNode =
+                  audioContext.createMediaStreamDestination();
+              sourceNode.connect(destinationNode);
+              sourceNode.connect(audioContext.destination);
+              const audioTrack = destinationNode.stream.getAudioTracks()[0];
+              return {
+                audioContext,
+                sourceNode,
+                destinationNode,
+                audioTrack,
+              };
+            });
     return audioObject.audioTrack;
   }
 

lib/text/text_engine.js

@@ -392,9 +392,7 @@ shaka.text.TextEngine = class {
     for (const caption of closedCaptions) {
       const id = caption.stream;
       const cue = caption.cue;
-      if (!captionsMap.has(id)) {
-        captionsMap.set(id, []);
-      }
+      captionsMap.getOrInsert(id, []);
 
       // Adjust CEA captions with respect to the timestamp offset of the video
       // stream in which they were embedded.
@@ -414,11 +412,10 @@ shaka.text.TextEngine = class {
     }
 
     for (const id of captionsMap.keys()) {
-      if (!this.closedCaptionsMap_.has(id)) {
-        this.closedCaptionsMap_.set(id, []);
-      }
+      const closedCaptions = this.closedCaptionsMap_.getOrInsertComputed(
+          id, () => []);
       for (const cue of captionsMap.get(id)) {
-        this.closedCaptionsMap_.get(id).push(cue);
+        closedCaptions.push(cue);
       }
     }
 

lib/transmuxer/aac_transmuxer.js

@@ -207,14 +207,9 @@ shaka.transmuxer.AacTransmuxer = class {
       stream: stream,
     };
     const mp4Generator = new shaka.util.Mp4Generator([streamInfo]);
-    let initSegment;
     const initSegmentKey = stream.id + '_' + reference.discontinuitySequence;
-    if (!this.initSegments.has(initSegmentKey)) {
-      initSegment = mp4Generator.initSegment();
-      this.initSegments.set(initSegmentKey, initSegment);
-    } else {
-      initSegment = this.initSegments.get(initSegmentKey);
-    }
+    const initSegment = this.initSegments.getOrInsertComputed(
+        initSegmentKey, () => mp4Generator.initSegment());
     const appendInitSegment = this.lastInitSegment_ !== initSegment;
     const segmentData = mp4Generator.segmentData();
     this.lastInitSegment_ = initSegment;

lib/transmuxer/ac3_transmuxer.js

@@ -201,14 +201,9 @@ shaka.transmuxer.Ac3Transmuxer = class {
       stream: stream,
     };
     const mp4Generator = new shaka.util.Mp4Generator([streamInfo]);
-    let initSegment;
     const initSegmentKey = stream.id + '_' + reference.discontinuitySequence;
-    if (!this.initSegments.has(initSegmentKey)) {
-      initSegment = mp4Generator.initSegment();
-      this.initSegments.set(initSegmentKey, initSegment);
-    } else {
-      initSegment = this.initSegments.get(initSegmentKey);
-    }
+    const initSegment = this.initSegments.getOrInsertComputed(
+        initSegmentKey, () => mp4Generator.initSegment());
     const appendInitSegment = this.lastInitSegment_ !== initSegment;
     const segmentData = mp4Generator.segmentData();
     this.lastInitSegment_ = initSegment;

lib/transmuxer/ec3_transmuxer.js

@@ -195,14 +195,9 @@ shaka.transmuxer.Ec3Transmuxer = class {
       stream: stream,
     };
     const mp4Generator = new shaka.util.Mp4Generator([streamInfo]);
-    let initSegment;
     const initSegmentKey = stream.id + '_' + reference.discontinuitySequence;
-    if (!this.initSegments.has(initSegmentKey)) {
-      initSegment = mp4Generator.initSegment();
-      this.initSegments.set(initSegmentKey, initSegment);
-    } else {
-      initSegment = this.initSegments.get(initSegmentKey);
-    }
+    const initSegment = this.initSegments.getOrInsertComputed(
+        initSegmentKey, () => mp4Generator.initSegment());
     const appendInitSegment = this.lastInitSegment_ !== initSegment;
     const segmentData = mp4Generator.segmentData();
     this.lastInitSegment_ = initSegment;

lib/transmuxer/mp3_transmuxer.js

@@ -188,14 +188,9 @@ shaka.transmuxer.Mp3Transmuxer = class {
       stream: stream,
     };
     const mp4Generator = new shaka.util.Mp4Generator([streamInfo]);
-    let initSegment;
     const initSegmentKey = stream.id + '_' + reference.discontinuitySequence;
-    if (!this.initSegments.has(initSegmentKey)) {
-      initSegment = mp4Generator.initSegment();
-      this.initSegments.set(initSegmentKey, initSegment);
-    } else {
-      initSegment = this.initSegments.get(initSegmentKey);
-    }
+    const initSegment = this.initSegments.getOrInsertComputed(
+        initSegmentKey, () => mp4Generator.initSegment());
     const appendInitSegment = this.lastInitSegment_ !== initSegment;
     const segmentData = mp4Generator.segmentData();
     this.lastInitSegment_ = initSegment;

lib/transmuxer/ts_transmuxer.js

@@ -288,14 +288,9 @@ shaka.transmuxer.TsTransmuxer = class {
     }
 
     const mp4Generator = new shaka.util.Mp4Generator(streamInfos);
-    let initSegment;
     const initSegmentKey = stream.id + '_' + reference.discontinuitySequence;
-    if (!this.initSegments.has(initSegmentKey)) {
-      initSegment = mp4Generator.initSegment();
-      this.initSegments.set(initSegmentKey, initSegment);
-    } else {
-      initSegment = this.initSegments.get(initSegmentKey);
-    }
+    const initSegment = this.initSegments.getOrInsertComputed(
+        initSegmentKey, () => mp4Generator.initSegment());
     const appendInitSegment = this.lastInitSegment_ !== initSegment;
     const segmentData = mp4Generator.segmentData();
     this.lastInitSegment_ = initSegment;

lib/util/multi_map.js

@@ -24,11 +24,7 @@ shaka.util.MultiMap = class {
    * @param {T} value
    */
   push(key, value) {
-    if (this.map_.has(key)) {
-      this.map_.get(key).push(value);
-    } else {
-      this.map_.set(key, [value]);
-    }
+    this.map_.getOrInsertComputed(key, () => []).push(value);
   }
 
 

lib/util/periods.js

@@ -1947,11 +1947,8 @@ shaka.util.PeriodCombiner = class {
    * @private
    */
   static getCodec_(codecs) {
-    if (!shaka.util.PeriodCombiner.memoizedCodecs.has(codecs)) {
-      const normalizedCodec = shaka.util.MimeUtils.getNormalizedCodec(codecs);
-      shaka.util.PeriodCombiner.memoizedCodecs.set(codecs, normalizedCodec);
-    }
-    return shaka.util.PeriodCombiner.memoizedCodecs.get(codecs);
+    return shaka.util.PeriodCombiner.memoizedCodecs.getOrInsertComputed(
+        codecs, () => shaka.util.MimeUtils.getNormalizedCodec(codecs));
   }
 
   /**

shaka-player.uncompiled.js

@@ -46,6 +46,7 @@ goog.require('shaka.offline.indexeddb.StorageMechanism');
 goog.require('shaka.polyfill.Aria');
 goog.require('shaka.polyfill.EmeEncryptionScheme');
 goog.require('shaka.polyfill.Fullscreen');
+goog.require('shaka.polyfill.Map');
 goog.require('shaka.polyfill.MCapEncryptionScheme');
 goog.require('shaka.polyfill.MediaSource');
 goog.require('shaka.polyfill.MediaCapabilities');

ui/language_utils.js

@@ -80,10 +80,7 @@ shaka.ui.LanguageUtils = class {
       if (!track.codecs) {
         continue;
       }
-      if (!codecsByLanguage.has(track.language)) {
-        codecsByLanguage.set(track.language, new Set());
-      }
-      codecsByLanguage.get(track.language).add(
+      codecsByLanguage.getOrInsertComputed(track.language, () => new Set()).add(
           shaka.util.MimeUtils.getNormalizedCodec(track.codecs));
     }
     const hasDifferentAudioCodecs = (language) =>

ui/localization.js

@@ -155,7 +155,7 @@ shaka.ui.Localization = class extends shaka.util.FakeEventTarget {
 
     // Make sure we have an entry for the locale because we are about to
     // write to it.
-    const table = this.localizations_.get(locale) || new Map();
+    const table = this.localizations_.getOrInsert(locale, new Map());
     localizations.forEach((value, id) => {
       // Set the value if we don't have an old value or if we are to replace
       // the old value with the new value.
@@ -163,7 +163,6 @@ shaka.ui.Localization = class extends shaka.util.FakeEventTarget {
         table.set(id, value);
       }
     });
-    this.localizations_.set(locale, table);
 
     // The data we use to make our map may have changed, update the map we pull
     // data from.