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denoland-deno/extensions/web/03_abort_signal.js
Luca Casonato 1fb2e23a67
feat(fetch): implement abort (#10863)
This commit introduces fetch aborting via an AbortSignal.
2021-06-06 15:37:17 +02:00

142 lines
3.4 KiB
JavaScript

// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
"use strict";
((window) => {
const webidl = window.__bootstrap.webidl;
const { setIsTrusted } = window.__bootstrap.event;
const add = Symbol("add");
const signalAbort = Symbol("signalAbort");
const remove = Symbol("remove");
const illegalConstructorKey = Symbol("illegalConstructorKey");
class AbortSignal extends EventTarget {
#aborted = false;
#abortAlgorithms = new Set();
static abort() {
const signal = new AbortSignal(illegalConstructorKey);
signal[signalAbort]();
return signal;
}
[add](algorithm) {
this.#abortAlgorithms.add(algorithm);
}
[signalAbort]() {
if (this.#aborted) {
return;
}
this.#aborted = true;
for (const algorithm of this.#abortAlgorithms) {
algorithm();
}
this.#abortAlgorithms.clear();
const event = new Event("abort");
setIsTrusted(event, true);
this.dispatchEvent(event);
}
[remove](algorithm) {
this.#abortAlgorithms.delete(algorithm);
}
constructor(key = null) {
if (key != illegalConstructorKey) {
throw new TypeError("Illegal constructor.");
}
super();
this[webidl.brand] = webidl.brand;
}
get aborted() {
return Boolean(this.#aborted);
}
get [Symbol.toStringTag]() {
return "AbortSignal";
}
}
defineEventHandler(AbortSignal.prototype, "abort");
class AbortController {
#signal = new AbortSignal(illegalConstructorKey);
get signal() {
return this.#signal;
}
abort() {
this.#signal[signalAbort]();
}
get [Symbol.toStringTag]() {
return "AbortController";
}
}
const handlerSymbol = Symbol("eventHandlers");
function makeWrappedHandler(handler) {
function wrappedHandler(...args) {
if (typeof wrappedHandler.handler !== "function") {
return;
}
return wrappedHandler.handler.call(this, ...args);
}
wrappedHandler.handler = handler;
return wrappedHandler;
}
// TODO(benjamingr) reuse this here and websocket where possible
function defineEventHandler(emitter, name) {
// HTML specification section 8.1.5.1
Object.defineProperty(emitter, `on${name}`, {
get() {
return this[handlerSymbol]?.get(name)?.handler;
},
set(value) {
if (!this[handlerSymbol]) {
this[handlerSymbol] = new Map();
}
let handlerWrapper = this[handlerSymbol]?.get(name);
if (handlerWrapper) {
handlerWrapper.handler = value;
} else {
handlerWrapper = makeWrappedHandler(value);
this.addEventListener(name, handlerWrapper);
}
this[handlerSymbol].set(name, handlerWrapper);
},
configurable: true,
enumerable: true,
});
}
webidl.converters["AbortSignal"] = webidl.createInterfaceConverter(
"AbortSignal",
AbortSignal,
);
function newSignal() {
return new AbortSignal(illegalConstructorKey);
}
function follow(followingSignal, parentSignal) {
if (parentSignal.aborted) {
followingSignal[signalAbort]();
} else {
parentSignal[add](() => followingSignal[signalAbort]());
}
}
window.AbortSignal = AbortSignal;
window.AbortController = AbortController;
window.__bootstrap.abortSignal = {
add,
signalAbort,
remove,
follow,
newSignal,
};
})(this);