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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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57
web/event_utils.js
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@ -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 }) {
return new Promise(function (resolve, reject) {
if (
typeof target !== "object" ||
!(name && typeof name === "string") ||
!(Number.isInteger(delay) && delay >= 0)
) {
throw new Error("waitOnEventOrTimeout - invalid parameters.");
}
async function waitOnEventOrTimeout({ target, name, delay = 0 }) {
if (
typeof target !== "object" ||
!(name && typeof name === "string") ||
!(Number.isInteger(delay) && delay >= 0)
) {
throw new Error("waitOnEventOrTimeout - invalid parameters.");
}
const { promise, resolve } = Promise.withResolvers();
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);
function handler(type) {
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);
const timeout = setTimeout(timeoutHandler, delay);
});
if (timeout) {
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;
}
/**