New: Implement Pledge.any()

src/pledge.js

@@ -9,7 +9,7 @@
 
 import { PledgeSymbol } from "./pledge-symbol.js";
 import { PledgeReactionJob, hostEnqueuePledgeJob } from "./pledge-jobs.js";
-import { isObject, isCallable, isConstructor } from "./utilities.js";
+import { isObject, isCallable, isConstructor, PledgeAggregateError } from "./utilities.js";
 import {
     isPledge,
     createResolvingFunctions,
@@ -86,6 +86,22 @@ export class Pledge {
         return this;
     }
 
+    static any(iterable) {
+
+        const C = this;
+        const pledgeCapability = new PledgeCapability(C);
+
+        try {
+            const pledgeResolve = getPledgeResolve(C);
+            const iteratorRecord = iterable[Symbol.iterator]();
+            const result = performPledgeAny(iteratorRecord, C, pledgeCapability, pledgeResolve);
+            return result;
+        } catch (error) {
+            pledgeCapability.reject(error);
+            return error;
+        }
+    }
+
     static race(iterable) {
 
         const C = this;
@@ -267,6 +283,85 @@ function getPledgeResolve(pledgeConstructor) {
     return pledgeResolve;
 }
 
+//-----------------------------------------------------------------------------
+// 26.6.4.3.1 PerformPromiseAny ( iteratorRecord, constructor, 
+//      resultCapability, promiseResolve )
+//-----------------------------------------------------------------------------
+
+function performPledgeAny(iteratorRecord, constructor, resultCapability, pledgeResolve) {
+
+    assertIsConstructor(constructor);
+    assertIsCallable(pledgeResolve);
+
+    const errors = [];
+    const remainingElementsCount = { value: 1 };
+    let index = 0;
+
+    for (const nextValue of iteratorRecord) {
+
+        errors.push(undefined);
+
+        const nextPledge = pledgeResolve(constructor, nextValue);
+        const rejectElement = createPledgeAnyRejectElement(index, errors, resultCapability, remainingElementsCount);
+
+        remainingElementsCount.value = remainingElementsCount.value + 1;
+        nextPledge.then(resultCapability.resolve, rejectElement);
+        index = index + 1;
+    }
+
+    remainingElementsCount.value = remainingElementsCount.value - 1;
+    if (remainingElementsCount.value === 0) {
+        const error = new PledgeAggregateError();
+        Object.defineProperty(error, "errors", {
+            configurable: true,
+            enumerable: false,
+            writable: true,
+            value: errors
+        });
+
+        resultCapability.reject(error);
+    }
+
+    return resultCapability.pledge;
+}
+
+//-----------------------------------------------------------------------------
+// 26.6.4.3.2 Promise.any Reject Element Functions
+//-----------------------------------------------------------------------------
+
+// Note: this function doesn't exist in the spec, I've added it for clarity
+
+function createPledgeAnyRejectElement(index, errors, pledgeCapability, remainingElementsCount) {
+
+    const alreadyCalled = { value: false };
+
+    return x => {
+
+        if (alreadyCalled.value) {
+            return;
+        }
+
+        alreadyCalled.value = true;
+
+        errors[index] = x;
+        remainingElementsCount.value = remainingElementsCount.value - 1;
+
+        if (remainingElementsCount.value === 0) {
+            const error = new PledgeAggregateError();
+            Object.defineProperty(error, "errors", {
+                configurable: true,
+                enumerable: false,
+                writable: true,
+                value: errors
+            });
+
+            return pledgeCapability.reject(error);
+
+        }
+
+    };
+}
+
 //-----------------------------------------------------------------------------
 // 26.6.4.5.1 PerformPromiseRace ( iteratorRecord, constructor,
 //      resultCapability, promiseResolve )

src/utilities.js

@@ -59,3 +59,36 @@ export function isCallable(argument) {
 export function isConstructor(argument) {
     return typeof argument === "function" && typeof argument.prototype !== "undefined";
 }
+
+
+//-----------------------------------------------------------------------------
+// 19.5.7 AggregateError Objects
+//-----------------------------------------------------------------------------
+
+export function PledgeAggregateError(errors=[], message) {
+
+    const O = new.target === undefined ? new PledgeAggregateError() : this;
+
+    if (typeof message !== "undefined") {
+        const msg = String(message);
+
+        Object.defineProperty(O, "message", {
+            value: msg,
+            writable: true,
+            enumerable: false,
+            configurable: true
+        });
+    }
+
+    // errors can be an iterable
+    const errorsList = [...errors];
+
+    Object.defineProperty(O, "errors", {
+        configurable: true,
+        enumerable: false,
+        writable: true,
+        value: errorsList
+    });
+
+    return O;
+}

tests/pledge.test.js

@@ -446,6 +446,75 @@ describe("Pledge", () => {
         });
     });
 
+    describe("Pledge.any()", () => {
+
+        it("should throw an error when `this` is not a constructor", () => {
+            expect(() => {
+                Pledge.any.call({}, []);
+            }).to.throw(/constructor/);
+        });
+
+        it("should return the first value that was resolved", done => {
+
+            const pledge = Pledge.any([
+                Pledge.resolve(42),
+                Pledge.resolve(43),
+                Pledge.resolve(44)
+            ]);
+
+            pledge.then(value => {
+                expect(value).to.equal(42);
+                done();
+            });
+
+        });
+
+        it("should return the second pledge resolution when it is resolved first", done => {
+
+            const pledge = Pledge.any([
+                Pledge.reject(42),
+                Pledge.resolve(43),
+                Pledge.resolve(44)
+            ]);
+
+            pledge.then(value => {
+                expect(value).to.equal(43);
+                done();
+            });
+
+        });
+
+        it("should return an aggregate error when all pledges are rejected", done => {
+
+            const pledge = Pledge.any([
+                Pledge.reject(42),
+                Pledge.reject(43),
+                Pledge.reject(44)
+            ]);
+
+            pledge.catch(reason => {
+                expect(reason.errors).to.deep.equal([42, 43, 44]);
+                done();
+            });
+
+        });
+
+        it("should return the third pledge value when it is resolved first", done => {
+
+            const pledge = Pledge.any([
+                delayResolvePledge(42, 500),
+                Pledge.reject(43),
+                Pledge.resolve(44)
+            ]);
+
+            pledge.then(value => {
+                expect(value).to.equal(44);
+                done();
+            });
+
+        });
+    });
+