lib: implement AbortSignal.abort()

Refs: whatwg/dom#960

PR-URL: #37693
Backport-PR-URL: #38386
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

Author: jasnell

.eslintrc.js

@@ -283,6 +283,7 @@ module.exports = {
   },
   globals: {
     AbortController: 'readable',
+    AbortSignal: 'readable',
     Atomics: 'readable',
     BigInt: 'readable',
     BigInt64Array: 'readable',

doc/api/globals.md

@@ -65,6 +65,15 @@ added: REPLACEME
 The `AbortSignal` is used to notify observers when the
 `abortController.abort()` method is called.
 
+#### Static method: `AbortSignal.abort()`
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {AbortSignal}
+
+Returns a new already aborted `AbortSignal`.
+
 #### Event: `'abort'`
 <!-- YAML
 added: REPLACEME

lib/internal/abort_controller.js

@@ -50,6 +50,10 @@ class AbortSignal extends EventTarget {
       aborted: this.aborted
     }, depth, options);
   }
+
+  static abort() {
+    return createAbortSignal(true);
+  }
 }
 
 Object.defineProperties(AbortSignal.prototype, {
@@ -65,10 +69,10 @@ ObjectDefineProperty(AbortSignal.prototype, SymbolToStringTag, {
 
 defineEventHandler(AbortSignal.prototype, 'abort');
 
-function createAbortSignal() {
+function createAbortSignal(aborted = false) {
   const signal = new EventTarget();
   ObjectSetPrototypeOf(signal, AbortSignal.prototype);
-  signal[kAborted] = false;
+  signal[kAborted] = aborted;
   return signal;
 }
 

test/parallel/test-abortcontroller.js

@@ -68,3 +68,8 @@ const { Event } = require('internal/event_target');
   strictEqual(toString(ac), '[object AbortController]');
   strictEqual(toString(ac.signal), '[object AbortSignal]');
 }
+
+{
+  const signal = AbortSignal.abort();
+  ok(signal.aborted);
+}