[api-minor] Replace the PromiseCapability with Promise.withResolvers()

This replaces our custom `PromiseCapability`-class with the new native `Promise.withResolvers()` functionality, which does *almost* the same thing[1]; please see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers

The only difference is that `PromiseCapability` also had a `settled`-getter, which was however not widely used and the call-sites can either be removed or re-factored to avoid it. In particular:
 - In `src/display/api.js` we can tweak the `PDFObjects`-class to use a "special" initial data-value and just compare against that, in order to replace the `settled`-state.
 - In `web/app.js` we change the only case to manually track the `settled`-state, which should hopefully be OK given how this is being used.
 - In `web/pdf_outline_viewer.js` we can remove the `settled`-checks, since the code should work just fine without it. The only thing that could potentially happen is that we try to `resolve` a Promise multiple times, which is however *not* a problem since the value of a Promise cannot be changed once fulfilled or rejected.
 - In `web/pdf_viewer.js` we can remove the `settled`-checks, since the code should work fine without them:
     - For the `_onePageRenderedCapability` case the `settled`-check is used in a `EventBus`-listener which is *removed* on its first (valid) invocation.
     - For the `_pagesCapability` case the `settled`-check is used in a print-related helper that works just fine with "only" the other checks.
 - In `test/unit/api_spec.js` we can change the few relevant cases to manually track the `settled`-state, since this is both simple and *test-only* code.

---
[1] In browsers/environments that lack native support, note [the compatibility data](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers#browser_compatibility), it'll be polyfilled via the `core-js` library (but only in `legacy` builds).

gulpfile.mjs

@@ -99,6 +99,13 @@ const AUTOPREFIXER_CONFIG = {
 // Default Babel targets used for generic, components, minified-pre
 const BABEL_TARGETS = ENV_TARGETS.join(", ");
 
+const BABEL_PRESET_ENV_OPTS = Object.freeze({
+  corejs: "3.36.1",
+  exclude: ["web.structured-clone"],
+  shippedProposals: true,
+  useBuiltIns: "usage",
+});
+
 const DEFINES = Object.freeze({
   SKIP_BABEL: true,
   TESTING: undefined,
@@ -303,17 +310,7 @@ function createWebpackConfig(
 
   const babelPresets = skipBabel
     ? undefined
-    : [
+    : [["@babel/preset-env", BABEL_PRESET_ENV_OPTS]];
-        [
-          "@babel/preset-env",
-          {
-            corejs: "3.36.1",
-            exclude: ["web.structured-clone"],
-            shippedProposals: true,
-            useBuiltIns: "usage",
-          },
-        ],
-      ];
   const babelPlugins = [
     [
       babelPluginPDFJSPreprocessor,
@@ -1542,7 +1539,12 @@ function buildLibHelper(bundleDefines, inputStream, outputDir) {
       sourceType: "module",
       presets: skipBabel
         ? undefined
-        : [["@babel/preset-env", { loose: false, modules: false }]],
+        : [
+            [
+              "@babel/preset-env",
+              { ...BABEL_PRESET_ENV_OPTS, loose: false, modules: false },
+            ],
+          ],
       plugins: [[babelPluginPDFJSPreprocessor, ctx]],
       targets: BABEL_TARGETS,
     }).code;

src/core/chunked_stream.js

@@ -14,7 +14,7 @@
  */
 
 import { arrayBuffersToBytes, MissingDataException } from "./core_utils.js";
-import { assert, PromiseCapability } from "../shared/util.js";
+import { assert } from "../shared/util.js";
 import { Stream } from "./stream.js";
 
 class ChunkedStream extends Stream {
@@ -273,7 +273,7 @@ class ChunkedStreamManager {
     this.progressiveDataLength = 0;
     this.aborted = false;
 
-    this._loadedStreamCapability = new PromiseCapability();
+    this._loadedStreamCapability = Promise.withResolvers();
   }
 
   sendRequest(begin, end) {
@@ -347,7 +347,7 @@ class ChunkedStreamManager {
       return Promise.resolve();
     }
 
-    const capability = new PromiseCapability();
+    const capability = Promise.withResolvers();
     this._promisesByRequest.set(requestId, capability);
 
     const chunksToRequest = [];

src/core/evaluator.js

@@ -25,7 +25,6 @@ import {
   isArrayEqual,
   normalizeUnicode,
   OPS,
-  PromiseCapability,
   shadow,
   stringToPDFString,
   TextRenderingMode,
@@ -1270,7 +1269,7 @@ class PartialEvaluator {
       return this.fontCache.get(font.cacheKey);
     }
 
-    const fontCapability = new PromiseCapability();
+    const { promise, resolve } = Promise.withResolvers();
 
     let preEvaluatedFont;
     try {
@@ -1328,10 +1327,10 @@ class PartialEvaluator {
     //       keys. Also, since `fontRef` is used when getting cached fonts,
     //       we'll not accidentally match fonts cached with the `fontID`.
     if (fontRefIsRef) {
-      this.fontCache.put(fontRef, fontCapability.promise);
+      this.fontCache.put(fontRef, promise);
     } else {
       font.cacheKey = `cacheKey_${fontID}`;
-      this.fontCache.put(font.cacheKey, fontCapability.promise);
+      this.fontCache.put(font.cacheKey, promise);
     }
 
     // Keep track of each font we translated so the caller can
@@ -1340,7 +1339,7 @@ class PartialEvaluator {
 
     this.translateFont(preEvaluatedFont)
       .then(translatedFont => {
-        fontCapability.resolve(
+        resolve(
           new TranslatedFont({
             loadedName: font.loadedName,
             font: translatedFont,
@@ -1350,10 +1349,10 @@ class PartialEvaluator {
         );
       })
       .catch(reason => {
-        // TODO fontCapability.reject?
+        // TODO reject?
         warn(`loadFont - translateFont failed: "${reason}".`);
 
-        fontCapability.resolve(
+        resolve(
           new TranslatedFont({
             loadedName: font.loadedName,
             font: new ErrorFont(
@@ -1364,7 +1363,7 @@ class PartialEvaluator {
           })
         );
       });
-    return fontCapability.promise;
+    return promise;
   }
 
   buildPath(operatorList, fn, args, parsingText = false) {

src/core/worker.js

@@ -22,7 +22,6 @@ import {
   isNodeJS,
   MissingPDFException,
   PasswordException,
-  PromiseCapability,
   setVerbosityLevel,
   stringToPDFString,
   UnexpectedResponseException,
@@ -48,7 +47,7 @@ class WorkerTask {
   constructor(name) {
     this.name = name;
     this.terminated = false;
-    this._capability = new PromiseCapability();
+    this._capability = Promise.withResolvers();
   }
 
   get finished() {
@@ -212,7 +211,7 @@ class WorkerMessageHandler {
         password,
         rangeChunkSize,
       };
-      const pdfManagerCapability = new PromiseCapability();
+      const pdfManagerCapability = Promise.withResolvers();
       let newPdfManager;
 
       if (data) {

src/display/api.js

@@ -28,7 +28,6 @@ import {
   MAX_IMAGE_SIZE_TO_CACHE,
   MissingPDFException,
   PasswordException,
-  PromiseCapability,
   RenderingIntentFlag,
   setVerbosityLevel,
   shadow,
@@ -577,7 +576,7 @@ class PDFDocumentLoadingTask {
   static #docId = 0;
 
   constructor() {
-    this._capability = new PromiseCapability();
+    this._capability = Promise.withResolvers();
     this._transport = null;
     this._worker = null;
 
@@ -674,7 +673,7 @@ class PDFDataRangeTransport {
     this._progressListeners = [];
     this._progressiveReadListeners = [];
     this._progressiveDoneListeners = [];
-    this._readyCapability = new PromiseCapability();
+    this._readyCapability = Promise.withResolvers();
   }
 
   /**
@@ -1461,7 +1460,7 @@ class PDFPageProxy {
     // If there's no displayReadyCapability yet, then the operatorList
     // was never requested before. Make the request and create the promise.
     if (!intentState.displayReadyCapability) {
-      intentState.displayReadyCapability = new PromiseCapability();
+      intentState.displayReadyCapability = Promise.withResolvers();
       intentState.operatorList = {
         fnArray: [],
         argsArray: [],
@@ -1588,7 +1587,7 @@ class PDFPageProxy {
     if (!intentState.opListReadCapability) {
       opListTask = Object.create(null);
       opListTask.operatorListChanged = operatorListChanged;
-      intentState.opListReadCapability = new PromiseCapability();
+      intentState.opListReadCapability = Promise.withResolvers();
       (intentState.renderTasks ||= new Set()).add(opListTask);
       intentState.operatorList = {
         fnArray: [],
@@ -2049,7 +2048,7 @@ class PDFWorker {
     this.destroyed = false;
     this.verbosity = verbosity;
 
-    this._readyCapability = new PromiseCapability();
+    this._readyCapability = Promise.withResolvers();
     this._port = null;
     this._webWorker = null;
     this._messageHandler = null;
@@ -2365,7 +2364,7 @@ class WorkerTransport {
     this._networkStream = networkStream;
     this._fullReader = null;
     this._lastProgress = null;
-    this.downloadInfoCapability = new PromiseCapability();
+    this.downloadInfoCapability = Promise.withResolvers();
 
     this.setupMessageHandler();
 
@@ -2471,7 +2470,7 @@ class WorkerTransport {
     }
 
     this.destroyed = true;
-    this.destroyCapability = new PromiseCapability();
+    this.destroyCapability = Promise.withResolvers();
 
     this.#passwordCapability?.reject(
       new Error("Worker was destroyed during onPassword callback")
@@ -2562,7 +2561,7 @@ class WorkerTransport {
     });
 
     messageHandler.on("ReaderHeadersReady", data => {
-      const headersCapability = new PromiseCapability();
+      const headersCapability = Promise.withResolvers();
       const fullReader = this._fullReader;
       fullReader.headersReady.then(() => {
         // If stream or range are disabled, it's our only way to report
@@ -2677,7 +2676,7 @@ class WorkerTransport {
     });
 
     messageHandler.on("PasswordRequest", exception => {
-      this.#passwordCapability = new PromiseCapability();
+      this.#passwordCapability = Promise.withResolvers();
 
       if (loadingTask.onPassword) {
         const updatePassword = password => {
@@ -3089,6 +3088,8 @@ class WorkerTransport {
   }
 }
 
+const INITIAL_DATA = Symbol("INITIAL_DATA");
+
 /**
  * A PDF document and page is built of many objects. E.g. there are objects for
  * fonts, images, rendering code, etc. These objects may get processed inside of
@@ -3105,8 +3106,8 @@ class PDFObjects {
    */
   #ensureObj(objId) {
     return (this.#objs[objId] ||= {
-      capability: new PromiseCapability(),
+      ...Promise.withResolvers(),
-      data: null,
+      data: INITIAL_DATA,
     });
   }
 
@@ -3127,7 +3128,7 @@ class PDFObjects {
     // not required to be resolved right now.
     if (callback) {
       const obj = this.#ensureObj(objId);
-      obj.capability.promise.then(() => callback(obj.data));
+      obj.promise.then(() => callback(obj.data));
       return null;
     }
     // If there isn't a callback, the user expects to get the resolved data
@@ -3135,7 +3136,7 @@ class PDFObjects {
     const obj = this.#objs[objId];
     // If there isn't an object yet or the object isn't resolved, then the
     // data isn't ready yet!
-    if (!obj?.capability.settled) {
+    if (!obj || obj.data === INITIAL_DATA) {
       throw new Error(`Requesting object that isn't resolved yet ${objId}.`);
     }
     return obj.data;
@@ -3147,7 +3148,7 @@ class PDFObjects {
    */
   has(objId) {
     const obj = this.#objs[objId];
-    return obj?.capability.settled ?? false;
+    return !!obj && obj.data !== INITIAL_DATA;
   }
 
   /**
@@ -3159,7 +3160,7 @@ class PDFObjects {
   resolve(objId, data = null) {
     const obj = this.#ensureObj(objId);
     obj.data = data;
-    obj.capability.resolve();
+    obj.resolve();
   }
 
   clear() {
@@ -3172,9 +3173,9 @@ class PDFObjects {
 
   *[Symbol.iterator]() {
     for (const objId in this.#objs) {
-      const { capability, data } = this.#objs[objId];
+      const { data } = this.#objs[objId];
 
-      if (!capability.settled) {
+      if (data === INITIAL_DATA) {
         continue;
       }
       yield [objId, data];
@@ -3283,7 +3284,7 @@ class InternalRenderTask {
     this._useRequestAnimationFrame =
       useRequestAnimationFrame === true && typeof window !== "undefined";
     this.cancelled = false;
-    this.capability = new PromiseCapability();
+    this.capability = Promise.withResolvers();
     this.task = new RenderTask(this);
     // caching this-bound methods
     this._cancelBound = this.cancel.bind(this);

src/display/fetch_stream.js

@@ -13,12 +13,7 @@
  * limitations under the License.
  */
 
-import {
+import { AbortException, assert, warn } from "../shared/util.js";
-  AbortException,
-  assert,
-  PromiseCapability,
-  warn,
-} from "../shared/util.js";
 import {
   createResponseStatusError,
   extractFilenameFromHeader,
@@ -118,7 +113,7 @@ class PDFFetchStreamReader {
     const source = stream.source;
     this._withCredentials = source.withCredentials || false;
     this._contentLength = source.length;
-    this._headersCapability = new PromiseCapability();
+    this._headersCapability = Promise.withResolvers();
     this._disableRange = source.disableRange || false;
     this._rangeChunkSize = source.rangeChunkSize;
     if (!this._rangeChunkSize && !this._disableRange) {
@@ -223,7 +218,7 @@ class PDFFetchStreamRangeReader {
     this._loaded = 0;
     const source = stream.source;
     this._withCredentials = source.withCredentials || false;
-    this._readCapability = new PromiseCapability();
+    this._readCapability = Promise.withResolvers();
     this._isStreamingSupported = !source.disableStream;
 
     this._abortController = new AbortController();

src/display/network.js

@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-import { assert, PromiseCapability, stringToBytes } from "../shared/util.js";
+import { assert, stringToBytes } from "../shared/util.js";
 import {
   createResponseStatusError,
   extractFilenameFromHeader,
@@ -255,7 +255,7 @@ class PDFNetworkStreamFullRequestReader {
     };
     this._url = source.url;
     this._fullRequestId = manager.requestFull(args);
-    this._headersReceivedCapability = new PromiseCapability();
+    this._headersReceivedCapability = Promise.withResolvers();
     this._disableRange = source.disableRange || false;
     this._contentLength = source.length; // Optional
     this._rangeChunkSize = source.rangeChunkSize;
@@ -375,7 +375,7 @@ class PDFNetworkStreamFullRequestReader {
     if (this._done) {
       return { value: undefined, done: true };
     }
-    const requestCapability = new PromiseCapability();
+    const requestCapability = Promise.withResolvers();
     this._requests.push(requestCapability);
     return requestCapability.promise;
   }
@@ -466,7 +466,7 @@ class PDFNetworkStreamRangeRequestReader {
     if (this._done) {
       return { value: undefined, done: true };
     }
-    const requestCapability = new PromiseCapability();
+    const requestCapability = Promise.withResolvers();
     this._requests.push(requestCapability);
     return requestCapability.promise;
   }

src/display/node_stream.js

@@ -18,7 +18,6 @@ import {
   assert,
   isNodeJS,
   MissingPDFException,
-  PromiseCapability,
 } from "../shared/util.js";
 import {
   extractFilenameFromHeader,
@@ -128,8 +127,8 @@ class BaseFullReader {
     this._isRangeSupported = !source.disableRange;
 
     this._readableStream = null;
-    this._readCapability = new PromiseCapability();
+    this._readCapability = Promise.withResolvers();
-    this._headersCapability = new PromiseCapability();
+    this._headersCapability = Promise.withResolvers();
   }
 
   get headersReady() {
@@ -163,7 +162,7 @@ class BaseFullReader {
 
     const chunk = this._readableStream.read();
     if (chunk === null) {
-      this._readCapability = new PromiseCapability();
+      this._readCapability = Promise.withResolvers();
       return this.read();
     }
     this._loaded += chunk.length;
@@ -230,7 +229,7 @@ class BaseRangeReader {
     this.onProgress = null;
     this._loaded = 0;
     this._readableStream = null;
-    this._readCapability = new PromiseCapability();
+    this._readCapability = Promise.withResolvers();
     const source = stream.source;
     this._isStreamingSupported = !source.disableStream;
   }
@@ -250,7 +249,7 @@ class BaseRangeReader {
 
     const chunk = this._readableStream.read();
     if (chunk === null) {
-      this._readCapability = new PromiseCapability();
+      this._readCapability = Promise.withResolvers();
       return this.read();
     }
     this._loaded += chunk.length;

src/display/text_layer.js

@@ -16,7 +16,7 @@
 /** @typedef {import("./display_utils").PageViewport} PageViewport */
 /** @typedef {import("./api").TextContent} TextContent */
 
-import { AbortException, PromiseCapability, Util } from "../shared/util.js";
+import { AbortException, Util } from "../shared/util.js";
 import { setLayerDimensions } from "./display_utils.js";
 
 /**
@@ -326,7 +326,7 @@ class TextLayerRenderTask {
     this._reader = null;
     this._textDivProperties = textDivProperties || new WeakMap();
     this._canceled = false;
-    this._capability = new PromiseCapability();
+    this._capability = Promise.withResolvers();
     this._layoutTextParams = {
       prevFontSize: null,
       prevFontFamily: null,
@@ -426,21 +426,21 @@ class TextLayerRenderTask {
    * @private
    */
   _render() {
-    const capability = new PromiseCapability();
+    const { promise, resolve, reject } = Promise.withResolvers();
     let styleCache = Object.create(null);
 
     if (this._isReadableStream) {
       const pump = () => {
         this._reader.read().then(({ value, done }) => {
           if (done) {
-            capability.resolve();
+            resolve();
             return;
           }
 
           Object.assign(styleCache, value.styles);
           this._processItems(value.items, styleCache);
           pump();
-        }, capability.reject);
+        }, reject);
       };
 
       this._reader = this._textContentSource.getReader();
@@ -448,12 +448,12 @@ class TextLayerRenderTask {
     } else if (this._textContentSource) {
       const { items, styles } = this._textContentSource;
       this._processItems(items, styles);
-      capability.resolve();
+      resolve();
     } else {
       throw new Error('No "textContentSource" parameter specified.');
     }
 
-    capability.promise.then(() => {
+    promise.then(() => {
       styleCache = null;
       render(this);
     }, this._capability.reject);

src/display/transport_stream.js

@@ -18,7 +18,7 @@
 // eslint-disable-next-line max-len
 /** @typedef {import("../interfaces").IPDFStreamRangeReader} IPDFStreamRangeReader */
 
-import { assert, PromiseCapability } from "../shared/util.js";
+import { assert } from "../shared/util.js";
 import { isPdfFile } from "./display_utils.js";
 
 /** @implements {IPDFStream} */
@@ -235,7 +235,7 @@ class PDFDataTransportStreamReader {
     if (this._done) {
       return { value: undefined, done: true };
     }
-    const requestCapability = new PromiseCapability();
+    const requestCapability = Promise.withResolvers();
     this._requests.push(requestCapability);
     return requestCapability.promise;
   }
@@ -300,7 +300,7 @@ class PDFDataTransportStreamRangeReader {
     if (this._done) {
       return { value: undefined, done: true };
     }
-    const requestCapability = new PromiseCapability();
+    const requestCapability = Promise.withResolvers();
     this._requests.push(requestCapability);
     return requestCapability.promise;
   }

src/pdf.js

@@ -39,7 +39,6 @@ import {
   OPS,
   PasswordResponses,
   PermissionFlag,
-  PromiseCapability,
   shadow,
   UnexpectedResponseException,
   Util,
@@ -119,7 +118,6 @@ export {
   PDFWorker,
   PermissionFlag,
   PixelsPerInch,
-  PromiseCapability,
   RenderingCancelledException,
   renderTextLayer,
   setLayerDimensions,

src/shared/message_handler.js

@@ -18,7 +18,6 @@ import {
   assert,
   MissingPDFException,
   PasswordException,
-  PromiseCapability,
   UnexpectedResponseException,
   UnknownErrorException,
   unreachable,
@@ -190,7 +189,7 @@ class MessageHandler {
    */
   sendWithPromise(actionName, data, transfers) {
     const callbackId = this.callbackId++;
-    const capability = new PromiseCapability();
+    const capability = Promise.withResolvers();
     this.callbackCapabilities[callbackId] = capability;
     try {
       this.comObj.postMessage(
@@ -228,7 +227,7 @@ class MessageHandler {
     return new ReadableStream(
       {
         start: controller => {
-          const startCapability = new PromiseCapability();
+          const startCapability = Promise.withResolvers();
           this.streamControllers[streamId] = {
             controller,
             startCall: startCapability,
@@ -252,7 +251,7 @@ class MessageHandler {
         },
 
         pull: controller => {
-          const pullCapability = new PromiseCapability();
+          const pullCapability = Promise.withResolvers();
           this.streamControllers[streamId].pullCall = pullCapability;
           comObj.postMessage({
             sourceName,
@@ -268,7 +267,7 @@ class MessageHandler {
 
         cancel: reason => {
           assert(reason instanceof Error, "cancel must have a valid reason");
-          const cancelCapability = new PromiseCapability();
+          const cancelCapability = Promise.withResolvers();
           this.streamControllers[streamId].cancelCall = cancelCapability;
           this.streamControllers[streamId].isClosed = true;
           comObj.postMessage({
@@ -305,7 +304,7 @@ class MessageHandler {
         // so when it changes from positive to negative,
         // set ready as unresolved promise.
         if (lastDesiredSize > 0 && this.desiredSize <= 0) {
-          this.sinkCapability = new PromiseCapability();
+          this.sinkCapability = Promise.withResolvers();
           this.ready = this.sinkCapability.promise;
         }
         comObj.postMessage(
@@ -349,7 +348,7 @@ class MessageHandler {
         });
       },
 
-      sinkCapability: new PromiseCapability(),
+      sinkCapability: Promise.withResolvers(),
       onPull: null,
       onCancel: null,
       isCancelled: false,

src/shared/util.js

@@ -1031,43 +1031,6 @@ function getModificationDate(date = new Date()) {
   return buffer.join("");
 }
 
-class PromiseCapability {
-  #settled = false;
-
-  constructor() {
-    /**
-     * @type {Promise<any>} The Promise object.
-     */
-    this.promise = new Promise((resolve, reject) => {
-      /**
-       * @type {function} Fulfills the Promise.
-       */
-      this.resolve = data => {
-        this.#settled = true;
-        resolve(data);
-      };
-
-      /**
-       * @type {function} Rejects the Promise.
-       */
-      this.reject = reason => {
-        if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
-          assert(reason instanceof Error, 'Expected valid "reason" argument.');
-        }
-        this.#settled = true;
-        reject(reason);
-      };
-    });
-  }
-
-  /**
-   * @type {boolean} If the Promise has been fulfilled/rejected.
-   */
-  get settled() {
-    return this.#settled;
-  }
-}
-
 let NormalizeRegex = null;
 let NormalizationMap = null;
 function normalizeUnicode(str) {
@@ -1154,7 +1117,6 @@ export {
   PasswordException,
   PasswordResponses,
   PermissionFlag,
-  PromiseCapability,
   RenderingIntentFlag,
   setVerbosityLevel,
   shadow,

test/driver.js

@@ -22,7 +22,6 @@ const {
   GlobalWorkerOptions,
   Outliner,
   PixelsPerInch,
-  PromiseCapability,
   renderTextLayer,
   shadow,
   XfaLayer,
@@ -1112,7 +1111,7 @@ class Driver {
   }
 
   _send(url, message) {
-    const capability = new PromiseCapability();
+    const { promise, resolve } = Promise.withResolvers();
     this.inflight.textContent = this.inFlightRequests++;
 
     fetch(url, {
@@ -1129,18 +1128,18 @@ class Driver {
         }
 
         this.inFlightRequests--;
-        capability.resolve();
+        resolve();
       })
       .catch(reason => {
         console.warn(`Driver._send failed (${url}): ${reason}`);
 
         this.inFlightRequests--;
-        capability.resolve();
+        resolve();
 
         this._send(url, message);
       });
 
-    return capability.promise;
+    return promise;
   }
 }
 

test/unit/api_spec.js

@@ -26,7 +26,6 @@ import {
   PasswordException,
   PasswordResponses,
   PermissionFlag,
-  PromiseCapability,
   UnknownErrorException,
 } from "../../src/shared/util.js";
 import {
@@ -156,13 +155,11 @@ describe("api", function () {
       const loadingTask = getDocument(basicApiGetDocumentParams);
       expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
 
-      const progressReportedCapability = new PromiseCapability();
+      const progressReportedCapability = Promise.withResolvers();
       // Attach the callback that is used to report loading progress;
       // similarly to how viewer.js works.
       loadingTask.onProgress = function (progressData) {
-        if (!progressReportedCapability.settled) {
+        progressReportedCapability.resolve(progressData);
-          progressReportedCapability.resolve(progressData);
-        }
       };
 
       const data = await Promise.all([
@@ -218,7 +215,7 @@ describe("api", function () {
       const loadingTask = getDocument(typedArrayPdf);
       expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
 
-      const progressReportedCapability = new PromiseCapability();
+      const progressReportedCapability = Promise.withResolvers();
       loadingTask.onProgress = function (data) {
         progressReportedCapability.resolve(data);
       };
@@ -248,7 +245,7 @@ describe("api", function () {
       const loadingTask = getDocument(arrayBufferPdf);
       expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
 
-      const progressReportedCapability = new PromiseCapability();
+      const progressReportedCapability = Promise.withResolvers();
       loadingTask.onProgress = function (data) {
         progressReportedCapability.resolve(data);
       };
@@ -306,8 +303,14 @@ describe("api", function () {
       const loadingTask = getDocument(buildGetDocumentParams("pr6531_1.pdf"));
       expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
 
-      const passwordNeededCapability = new PromiseCapability();
+      const passwordNeededCapability = {
-      const passwordIncorrectCapability = new PromiseCapability();
+        ...Promise.withResolvers(),
+        settled: false,
+      };
+      const passwordIncorrectCapability = {
+        ...Promise.withResolvers(),
+        settled: false,
+      };
       // Attach the callback that is used to request a password;
       // similarly to how the default viewer handles passwords.
       loadingTask.onPassword = function (updatePassword, reason) {
@@ -315,6 +318,7 @@ describe("api", function () {
           reason === PasswordResponses.NEED_PASSWORD &&
           !passwordNeededCapability.settled
         ) {
+          passwordNeededCapability.settled = true;
           passwordNeededCapability.resolve();
 
           updatePassword("qwerty"); // Provide an incorrect password.
@@ -324,6 +328,7 @@ describe("api", function () {
           reason === PasswordResponses.INCORRECT_PASSWORD &&
           !passwordIncorrectCapability.settled
         ) {
+          passwordIncorrectCapability.settled = true;
           passwordIncorrectCapability.resolve();
 
           updatePassword("asdfasdf"); // Provide the correct password.

test/unit/message_handler_spec.js

@@ -15,7 +15,6 @@
 
 import {
   AbortException,
-  PromiseCapability,
   UnknownErrorException,
 } from "../../src/shared/util.js";
 import { LoopbackPort } from "../../src/display/api.js";
@@ -336,7 +335,7 @@ describe("message_handler", function () {
     it("should ignore any pull after close is called", async function () {
       let log = "";
       const port = new LoopbackPort();
-      const capability = new PromiseCapability();
+      const { promise, resolve } = Promise.withResolvers();
       const messageHandler2 = new MessageHandler("worker", "main", port);
       messageHandler2.on("fakeHandler", (data, sink) => {
         sink.onPull = function () {
@@ -350,7 +349,7 @@ describe("message_handler", function () {
           log += "1";
           sink.enqueue([1, 2, 3, 4], 4);
         });
-        return capability.promise.then(() => {
+        return promise.then(() => {
           sink.close();
         });
       });
@@ -371,8 +370,8 @@ describe("message_handler", function () {
       await sleep(10);
       expect(log).toEqual("01");
 
-      capability.resolve();
+      resolve();
-      await capability.promise;
+      await promise;
 
       let result = await reader.read();
       expect(result.value).toEqual([1, 2, 3, 4]);

test/unit/pdf_spec.js

@@ -29,7 +29,6 @@ import {
   OPS,
   PasswordResponses,
   PermissionFlag,
-  PromiseCapability,
   shadow,
   UnexpectedResponseException,
   Util,
@@ -105,7 +104,6 @@ const expectedAPI = Object.freeze({
   PDFWorker,
   PermissionFlag,
   PixelsPerInch,
-  PromiseCapability,
   RenderingCancelledException,
   renderTextLayer,
   setLayerDimensions,

test/unit/util_spec.js

@@ -17,7 +17,6 @@ import {
   bytesToString,
   createValidAbsoluteUrl,
   getModificationDate,
-  PromiseCapability,
   string32,
   stringToBytes,
   stringToPDFString,
@@ -223,37 +222,6 @@ describe("util", function () {
     });
   });
 
-  describe("PromiseCapability", function () {
-    it("should resolve with correct data", async function () {
-      const promiseCapability = new PromiseCapability();
-      expect(promiseCapability.settled).toEqual(false);
-
-      promiseCapability.resolve({ test: "abc" });
-
-      const data = await promiseCapability.promise;
-      expect(promiseCapability.settled).toEqual(true);
-      expect(data).toEqual({ test: "abc" });
-    });
-
-    it("should reject with correct reason", async function () {
-      const promiseCapability = new PromiseCapability();
-      expect(promiseCapability.settled).toEqual(false);
-
-      promiseCapability.reject(new Error("reason"));
-
-      try {
-        await promiseCapability.promise;
-
-        // Shouldn't get here.
-        expect(false).toEqual(true);
-      } catch (reason) {
-        expect(promiseCapability.settled).toEqual(true);
-        expect(reason instanceof Error).toEqual(true);
-        expect(reason.message).toEqual("reason");
-      }
-    });
-  });
-
   describe("getModificationDate", function () {
     it("should get a correctly formatted date", function () {
       const date = new Date(Date.UTC(3141, 5, 9, 2, 6, 53));

web/app.js

@@ -46,7 +46,6 @@ import {
   isPdfFile,
   MissingPDFException,
   PDFWorker,
-  PromiseCapability,
   shadow,
   UnexpectedResponseException,
   version,
@@ -92,7 +91,10 @@ const ViewOnLoad = {
 
 const PDFViewerApplication = {
   initialBookmark: document.location.hash.substring(1),
-  _initializedCapability: new PromiseCapability(),
+  _initializedCapability: {
+    ...Promise.withResolvers(),
+    settled: false,
+  },
   appConfig: null,
   pdfDocument: null,
   pdfLoadingTask: null,
@@ -240,6 +242,7 @@ const PDFViewerApplication = {
     this.bindEvents();
     this.bindWindowEvents();
 
+    this._initializedCapability.settled = true;
     this._initializedCapability.resolve();
   },
 

web/event_utils.js

@@ -35,39 +35,40 @@ const WaitOnType = {
  * @param {WaitOnEventOrTimeoutParameters}
  * @returns {Promise} A promise that is resolved with a {WaitOnType} value.
  */
-function waitOnEventOrTimeout({ target, name, delay = 0 }) {
+async function waitOnEventOrTimeout({ target, name, delay = 0 }) {
-  return new Promise(function (resolve, reject) {
+  if (
-    if (
+    typeof target !== "object" ||
-      typeof target !== "object" ||
+    !(name && typeof name === "string") ||
-      !(name && typeof name === "string") ||
+    !(Number.isInteger(delay) && delay >= 0)
-      !(Number.isInteger(delay) && delay >= 0)
+  ) {
-    ) {
+    throw new Error("waitOnEventOrTimeout - invalid parameters.");
-      throw new Error("waitOnEventOrTimeout - invalid parameters.");
+  }
-    }
+  const { promise, resolve } = Promise.withResolvers();
 
-    function handler(type) {
+  function handler(type) {
-      if (target instanceof EventBus) {
-        target._off(name, eventHandler);
-      } else {
-        target.removeEventListener(name, eventHandler);
-      }
-
-      if (timeout) {
-        clearTimeout(timeout);
-      }
-      resolve(type);
-    }
-
-    const eventHandler = handler.bind(null, WaitOnType.EVENT);
     if (target instanceof EventBus) {
-      target._on(name, eventHandler);
+      target._off(name, eventHandler);
     } else {
-      target.addEventListener(name, eventHandler);
+      target.removeEventListener(name, eventHandler);
     }
 
-    const timeoutHandler = handler.bind(null, WaitOnType.TIMEOUT);
+    if (timeout) {
-    const timeout = setTimeout(timeoutHandler, delay);
+      clearTimeout(timeout);
-  });
+    }
+    resolve(type);
+  }
+
+  const eventHandler = handler.bind(null, WaitOnType.EVENT);
+  if (target instanceof EventBus) {
+    target._on(name, eventHandler);
+  } else {
+    target.addEventListener(name, eventHandler);
+  }
+
+  const timeoutHandler = handler.bind(null, WaitOnType.TIMEOUT);
+  const timeout = setTimeout(timeoutHandler, delay);
+
+  return promise;
 }
 
 /**

web/password_prompt.js

@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-import { PasswordResponses, PromiseCapability } from "pdfjs-lib";
+import { PasswordResponses } from "pdfjs-lib";
 
 /**
  * @typedef {Object} PasswordPromptOptions
@@ -64,10 +64,8 @@ class PasswordPrompt {
   }
 
   async open() {
-    if (this.#activeCapability) {
+    await this.#activeCapability?.promise;
-      await this.#activeCapability.promise;
+    this.#activeCapability = Promise.withResolvers();
-    }
-    this.#activeCapability = new PromiseCapability();
 
     try {
       await this.overlayManager.open(this.dialog);

web/pdf_attachment_viewer.js

@@ -13,8 +13,8 @@
  * limitations under the License.
  */
 
-import { getFilenameFromUrl, PromiseCapability } from "pdfjs-lib";
 import { BaseTreeViewer } from "./base_tree_viewer.js";
+import { getFilenameFromUrl } from "pdfjs-lib";
 import { waitOnEventOrTimeout } from "./event_utils.js";
 
 /**
@@ -50,7 +50,7 @@ class PDFAttachmentViewer extends BaseTreeViewer {
     if (!keepRenderedCapability) {
       // The only situation in which the `_renderedCapability` should *not* be
       // replaced is when appending FileAttachment annotations.
-      this._renderedCapability = new PromiseCapability();
+      this._renderedCapability = Promise.withResolvers();
     }
     this._pendingDispatchEvent = false;
   }

web/pdf_document_properties.js

@@ -14,7 +14,7 @@
  */
 
 import { getPageSizeInches, isPortraitOrientation } from "./ui_utils.js";
-import { PDFDateString, PromiseCapability } from "pdfjs-lib";
+import { PDFDateString } from "pdfjs-lib";
 
 const DEFAULT_FIELD_CONTENT = "-";
 
@@ -200,7 +200,7 @@ class PDFDocumentProperties {
     this.pdfDocument = null;
 
     this.#fieldData = null;
-    this._dataAvailableCapability = new PromiseCapability();
+    this._dataAvailableCapability = Promise.withResolvers();
     this._currentPageNumber = 1;
     this._pagesRotation = 0;
   }

web/pdf_find_controller.js

@@ -19,7 +19,6 @@
 
 import { binarySearchFirstItem, scrollIntoView } from "./ui_utils.js";
 import { getCharacterType, getNormalizeWithNFKC } from "./pdf_find_utils.js";
-import { PromiseCapability } from "pdfjs-lib";
 
 const FindState = {
   FOUND: 0,
@@ -576,7 +575,7 @@ class PDFFindController {
     clearTimeout(this._findTimeout);
     this._findTimeout = null;
 
-    this._firstPageCapability = new PromiseCapability();
+    this._firstPageCapability = Promise.withResolvers();
   }
 
   /**
@@ -836,14 +835,14 @@ class PDFFindController {
       return;
     }
 
-    let promise = Promise.resolve();
+    let deferred = Promise.resolve();
     const textOptions = { disableNormalization: true };
     for (let i = 0, ii = this._linkService.pagesCount; i < ii; i++) {
-      const extractTextCapability = new PromiseCapability();
+      const { promise, resolve } = Promise.withResolvers();
-      this._extractTextPromises[i] = extractTextCapability.promise;
+      this._extractTextPromises[i] = promise;
 
       // eslint-disable-next-line arrow-body-style
-      promise = promise.then(() => {
+      deferred = deferred.then(() => {
         return this._pdfDocument
           .getPage(i + 1)
           .then(pdfPage => pdfPage.getTextContent(textOptions))
@@ -864,7 +863,7 @@ class PDFFindController {
                 this._pageDiffs[i],
                 this._hasDiacritics[i],
               ] = normalize(strBuf.join(""));
-              extractTextCapability.resolve();
+              resolve();
             },
             reason => {
               console.error(
@@ -875,7 +874,7 @@ class PDFFindController {
               this._pageContents[i] = "";
               this._pageDiffs[i] = null;
               this._hasDiacritics[i] = false;
-              extractTextCapability.resolve();
+              resolve();
             }
           );
       });

web/pdf_outline_viewer.js

@@ -14,7 +14,6 @@
  */
 
 import { BaseTreeViewer } from "./base_tree_viewer.js";
-import { PromiseCapability } from "pdfjs-lib";
 import { SidebarView } from "./ui_utils.js";
 
 /**
@@ -54,14 +53,9 @@ class PDFOutlineViewer extends BaseTreeViewer {
 
       // If the capability is still pending, see the `_dispatchEvent`-method,
       // we know that the `currentOutlineItem`-button can be enabled here.
-      if (
+      this._currentOutlineItemCapability?.resolve(
-        this._currentOutlineItemCapability &&
+        /* enabled = */ this._isPagesLoaded
-        !this._currentOutlineItemCapability.settled
+      );
-      ) {
-        this._currentOutlineItemCapability.resolve(
-          /* enabled = */ this._isPagesLoaded
-        );
-      }
     });
     this.eventBus._on("sidebarviewchanged", evt => {
       this._sidebarView = evt.view;
@@ -76,12 +70,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
     this._currentPageNumber = 1;
     this._isPagesLoaded = null;
 
-    if (
+    this._currentOutlineItemCapability?.resolve(/* enabled = */ false);
-      this._currentOutlineItemCapability &&
-      !this._currentOutlineItemCapability.settled
-    ) {
-      this._currentOutlineItemCapability.resolve(/* enabled = */ false);
-    }
     this._currentOutlineItemCapability = null;
   }
 
@@ -89,7 +78,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
    * @private
    */
   _dispatchEvent(outlineCount) {
-    this._currentOutlineItemCapability = new PromiseCapability();
+    this._currentOutlineItemCapability = Promise.withResolvers();
     if (
       outlineCount === 0 ||
       this._pdfDocument?.loadingParams.disableAutoFetch
@@ -307,7 +296,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
     if (this._pageNumberToDestHashCapability) {
       return this._pageNumberToDestHashCapability.promise;
     }
-    this._pageNumberToDestHashCapability = new PromiseCapability();
+    this._pageNumberToDestHashCapability = Promise.withResolvers();
 
     const pageNumberToDestHash = new Map(),
       pageNumberNesting = new Map();

web/pdf_scripting_manager.js

@@ -16,7 +16,7 @@
 /** @typedef {import("./event_utils").EventBus} EventBus */
 
 import { apiPageLayoutToViewerModes, RenderingStates } from "./ui_utils.js";
-import { PromiseCapability, shadow } from "pdfjs-lib";
+import { shadow } from "pdfjs-lib";
 
 /**
  * @typedef {Object} PDFScriptingManagerOptions
@@ -199,7 +199,7 @@ class PDFScriptingManager {
       return;
     }
     await this.#willPrintCapability?.promise;
-    this.#willPrintCapability = new PromiseCapability();
+    this.#willPrintCapability = Promise.withResolvers();
     try {
       await this.#scripting.dispatchEventInSandbox({
         id: "doc",
@@ -344,7 +344,7 @@ class PDFScriptingManager {
       visitedPages = this._visitedPages;
 
     if (initialize) {
-      this.#closeCapability = new PromiseCapability();
+      this.#closeCapability = Promise.withResolvers();
     }
     if (!this.#closeCapability) {
       return; // Scripting isn't fully initialized yet.
@@ -406,7 +406,7 @@ class PDFScriptingManager {
   }
 
   #initScripting() {
-    this.#destroyCapability = new PromiseCapability();
+    this.#destroyCapability = Promise.withResolvers();
 
     if (this.#scripting) {
       throw new Error("#initScripting: Scripting already exists.");

web/pdf_viewer.js

@@ -34,7 +34,6 @@ import {
   AnnotationMode,
   PermissionFlag,
   PixelsPerInch,
-  PromiseCapability,
   shadow,
   version,
 } from "pdfjs-lib";
@@ -362,10 +361,7 @@ class PDFViewer {
   get pageViewsReady() {
     // Prevent printing errors when 'disableAutoFetch' is set, by ensuring
     // that *all* pages have in fact been completely loaded.
-    return (
+    return this._pages.every(pageView => pageView?.pdfPage);
-      this._pagesCapability.settled &&
-      this._pages.every(pageView => pageView?.pdfPage)
-    );
   }
 
   /**
@@ -823,7 +819,7 @@ class PDFViewer {
     this.eventBus._on("pagerender", this._onBeforeDraw);
 
     this._onAfterDraw = evt => {
-      if (evt.cssTransform || this._onePageRenderedCapability.settled) {
+      if (evt.cssTransform) {
         return;
       }
       this._onePageRenderedCapability.resolve({ timestamp: evt.timestamp });
@@ -1075,9 +1071,9 @@ class PDFViewer {
     this._location = null;
     this._pagesRotation = 0;
     this._optionalContentConfigPromise = null;
-    this._firstPageCapability = new PromiseCapability();
+    this._firstPageCapability = Promise.withResolvers();
-    this._onePageRenderedCapability = new PromiseCapability();
+    this._onePageRenderedCapability = Promise.withResolvers();
-    this._pagesCapability = new PromiseCapability();
+    this._pagesCapability = Promise.withResolvers();
     this._scrollMode = ScrollMode.VERTICAL;
     this._previousScrollMode = ScrollMode.UNKNOWN;
     this._spreadMode = SpreadMode.NONE;

web/pdfjs.js

@@ -58,7 +58,6 @@ const {
   PDFWorker,
   PermissionFlag,
   PixelsPerInch,
-  PromiseCapability,
   RenderingCancelledException,
   renderTextLayer,
   setLayerDimensions,
@@ -107,7 +106,6 @@ export {
   PDFWorker,
   PermissionFlag,
   PixelsPerInch,
-  PromiseCapability,
   RenderingCancelledException,
   renderTextLayer,
   setLayerDimensions,