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

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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).
This commit is contained in:
Jonas Jenwald 2024-03-28 16:42:37 +01:00
parent 55db43966e
commit e4d0e84802
28 changed files with 159 additions and 252 deletions
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9
test/unit/message_handler_spec.js
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@ -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();
await capability.promise;
resolve();
await promise;
let result = await reader.read();
expect(result.value).toEqual([1, 2, 3, 4]);