Normative: Always use CopyDataProperties for object copy/merge

polyfill/lib/calendar.mjs

@@ -31,8 +31,8 @@ const ArraySort = Array.prototype.sort;
 const MathAbs = Math.abs;
 const MathFloor = Math.floor;
 const ObjectAssign = Object.assign;
+const ObjectCreate = Object.create;
 const ObjectEntries = Object.entries;
-const ObjectKeys = Object.keys;
 
 const impl = {};
 
@@ -265,23 +265,17 @@ impl['iso8601'] = {
     return fields;
   },
   mergeFields(fields, additionalFields) {
+    fields = ES.ToObject(fields);
+    additionalFields = ES.ToObject(additionalFields);
     const merged = {};
-    const keys = ObjectKeys(fields);
-    for (let index = 0; index < keys.length; index++) {
-      const nextKey = keys[index];
-      if (nextKey === 'month' || nextKey === 'monthCode') continue;
-      merged[nextKey] = fields[nextKey];
-    }
-    const newKeys = ObjectKeys(additionalFields);
-    for (let index = 0; index < newKeys.length; index++) {
-      const nextKey = newKeys[index];
-      merged[nextKey] = additionalFields[nextKey];
-    }
-    if (!ES.Call(ArrayIncludes, newKeys, ['month']) && !ES.Call(ArrayIncludes, newKeys, ['monthCode'])) {
-      const { month, monthCode } = fields;
-      if (month !== undefined) merged.month = month;
-      if (monthCode !== undefined) merged.monthCode = monthCode;
+    ES.CopyDataProperties(merged, fields, [], [undefined]);
+    const additionalFieldsCopy = ObjectCreate(null);
+    ES.CopyDataProperties(additionalFieldsCopy, additionalFields, [], [undefined]);
+    if ('month' in additionalFieldsCopy || 'monthCode' in additionalFieldsCopy) {
+      delete merged.month;
+      delete merged.monthCode;
     }
+    ES.CopyDataProperties(merged, additionalFieldsCopy, []);
     return merged;
   },
   dateAdd(date, years, months, weeks, days, overflow, calendar) {
@@ -1917,8 +1911,13 @@ const nonIsoGeneralImpl = {
     return fields;
   },
   mergeFields(fields, additionalFields) {
-    const fieldsCopy = { ...fields };
-    const additionalFieldsCopy = { ...additionalFields };
+    fields = ES.ToObject(fields);
+    additionalFields = ES.ToObject(additionalFields);
+    const fieldsCopy = {};
+    ES.CopyDataProperties(fieldsCopy, fields, [], [undefined]);
+    const additionalFieldsCopy = {};
+    ES.CopyDataProperties(additionalFieldsCopy, additionalFields, [], [undefined]);
+
     // era and eraYear are intentionally unused
     // eslint-disable-next-line @typescript-eslint/no-unused-vars
     const { month, monthCode, year, era, eraYear, ...original } = fieldsCopy;

polyfill/lib/ecmascript.mjs

@@ -20,17 +20,29 @@ const ObjectEntries = Object.entries;
 const StringPrototypeSlice = String.prototype.slice;
 
 import bigInt from 'big-integer';
+import callBound from 'call-bind/callBound';
 import Call from 'es-abstract/2022/Call.js';
+import CreateDataPropertyOrThrow from 'es-abstract/2022/CreateDataPropertyOrThrow.js';
+import Get from 'es-abstract/2022/Get.js';
 import GetMethod from 'es-abstract/2022/GetMethod.js';
+import IsArray from 'es-abstract/2022/IsArray.js';
 import IsIntegralNumber from 'es-abstract/2022/IsIntegralNumber.js';
 import ToIntegerOrInfinity from 'es-abstract/2022/ToIntegerOrInfinity.js';
+import IsPropertyKey from 'es-abstract/2022/IsPropertyKey.js';
+import SameValue from 'es-abstract/2022/SameValue.js';
 import ToLength from 'es-abstract/2022/ToLength.js';
 import ToNumber from 'es-abstract/2022/ToNumber.js';
+import ToObject from 'es-abstract/2022/ToObject.js';
 import ToPrimitive from 'es-abstract/2022/ToPrimitive.js';
 import ToString from 'es-abstract/2022/ToString.js';
 import Type from 'es-abstract/2022/Type.js';
 import HasOwnProperty from 'es-abstract/2022/HasOwnProperty.js';
 
+import every from 'es-abstract/helpers/every.js';
+import forEach from 'es-abstract/helpers/forEach.js';
+import OwnPropertyKeys from 'es-abstract/helpers/OwnPropertyKeys.js';
+import some from 'es-abstract/helpers/some.js';
+
 import { GetIntrinsic } from './intrinsicclass.mjs';
 import {
   CreateSlots,
@@ -67,6 +79,9 @@ import {
   NANOSECONDS
 } from './slots.mjs';
 
+const $TypeError = GetIntrinsic('%TypeError%');
+const $isEnumerable = callBound('Object.prototype.propertyIsEnumerable');
+
 const DAY_SECONDS = 86400;
 const DAY_NANOS = bigInt(DAY_SECONDS).multiply(1e9);
 const NS_MIN = bigInt(-DAY_SECONDS).multiply(1e17);
@@ -205,6 +220,7 @@ const ES2022 = {
   ToIntegerOrInfinity,
   ToLength,
   ToNumber,
+  ToObject,
   ToPrimitive,
   ToString,
   Type
@@ -232,6 +248,48 @@ function getIntlDateTimeFormatEnUsForTimeZone(timeZoneIdentifier) {
 }
 
 export const ES = ObjectAssign({}, ES2022, {
+  // copied from es-abstract/2022/CopyDataProperties.js
+  // with modifications per Temporal spec/mainadditions.html
+  CopyDataProperties: (target, source, excludedKeys, excludedValues) => {
+    if (Type(target) !== 'Object') {
+      throw new $TypeError('Assertion failed: "target" must be an Object');
+    }
+
+    if (!IsArray(excludedKeys) || !every(excludedKeys, IsPropertyKey)) {
+      throw new $TypeError('Assertion failed: "excludedKeys" must be a List of Property Keys');
+    }
+
+    if (typeof source === 'undefined' || source === null) {
+      return target;
+    }
+
+    var from = ToObject(source);
+
+    var keys = OwnPropertyKeys(from);
+    forEach(keys, function (nextKey) {
+      var excluded = some(excludedKeys, function (e) {
+        return SameValue(e, nextKey) === true;
+      });
+
+      var enumerable =
+        $isEnumerable(from, nextKey) ||
+        // this is to handle string keys being non-enumerable in older engines
+        (typeof source === 'string' && nextKey >= 0 && IsIntegralNumber(ToNumber(nextKey)));
+      if (excluded === false && enumerable) {
+        var propValue = Get(from, nextKey);
+        if (excludedValues !== undefined) {
+          forEach(excludedValues, function (e) {
+            if (SameValue(e, propValue) === true) {
+              excluded = true;
+            }
+          });
+        }
+        if (excluded === false) CreateDataPropertyOrThrow(target, nextKey, propValue);
+      }
+    });
+
+    return target;
+  },
   ToPositiveInteger: ToPositiveInteger,
   ToIntegerThrowOnInfinity,
   ToIntegerWithoutRounding,
@@ -931,10 +989,6 @@ export const ES = ObjectAssign({}, ES2022, {
     if (UNITS_DESCENDING.indexOf(unit1) > UNITS_DESCENDING.indexOf(unit2)) return unit2;
     return unit1;
   },
-  MergeLargestUnitOption: (options, largestUnit) => {
-    if (options === undefined) options = ObjectCreate(null);
-    return ObjectAssign(ObjectCreate(null), options, { largestUnit });
-  },
   PrepareTemporalFields: (
     bag,
     fields,
@@ -3364,7 +3418,9 @@ export const ES = ObjectAssign({}, ES2022, {
     const date1 = ES.CreateTemporalDate(y1, mon1, d1, calendar);
     const date2 = ES.CreateTemporalDate(y2, mon2, d2, calendar);
     const dateLargestUnit = ES.LargerOfTwoTemporalUnits('day', largestUnit);
-    const untilOptions = ES.MergeLargestUnitOption(options, dateLargestUnit);
+    const untilOptions = ObjectCreate(null);
+    ES.CopyDataProperties(untilOptions, options, []);
+    untilOptions.largestUnit = dateLargestUnit;
     let { years, months, weeks, days } = ES.CalendarDateUntil(calendar, date1, date2, untilOptions);
     // Signs of date part and time part may not agree; balance them together
     ({ days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds } = ES.BalanceDuration(
@@ -3506,7 +3562,9 @@ export const ES = ObjectAssign({}, ES2022, {
     if (operation === 'since') roundingMode = ES.NegateTemporalRoundingMode(roundingMode);
     const roundingIncrement = ES.ToTemporalRoundingIncrement(options, undefined, false);
 
-    const untilOptions = ES.MergeLargestUnitOption(options, largestUnit);
+    const untilOptions = ObjectCreate(null);
+    ES.CopyDataProperties(untilOptions, options, []);
+    untilOptions.largestUnit = largestUnit;
     let { years, months, weeks, days } = ES.CalendarDateUntil(calendar, plainDate, other, untilOptions);
 
     if (smallestUnit !== 'day' || roundingIncrement !== 1) {
@@ -3739,7 +3797,9 @@ export const ES = ObjectAssign({}, ES2022, {
     thisFields.day = 1;
     const thisDate = ES.CalendarDateFromFields(calendar, thisFields);
 
-    const untilOptions = ES.MergeLargestUnitOption(options, largestUnit);
+    const untilOptions = ObjectCreate(null);
+    ES.CopyDataProperties(untilOptions, options, []);
+    untilOptions.largestUnit = largestUnit;
     let { years, months } = ES.CalendarDateUntil(calendar, thisDate, otherDate, untilOptions);
 
     if (smallestUnit !== 'month' || roundingIncrement !== 1) {
@@ -3811,7 +3871,9 @@ export const ES = ObjectAssign({}, ES2022, {
             'or smaller because day lengths can vary between time zones due to DST or time zone offset changes.'
         );
       }
-      const untilOptions = ES.MergeLargestUnitOption(options, largestUnit);
+      const untilOptions = ObjectCreate(null);
+      ES.CopyDataProperties(untilOptions, options, []);
+      untilOptions.largestUnit = largestUnit;
       ({ years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds } =
         ES.DifferenceZonedDateTime(ns1, ns2, timeZone, calendar, largestUnit, untilOptions));
       ({ years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds } =
@@ -4305,7 +4367,8 @@ export const ES = ObjectAssign({}, ES2022, {
     const startDate = ES.CalendarDateFromFields(calendar, fields);
     const Duration = GetIntrinsic('%Temporal.Duration%');
     const durationToAdd = new Duration(years, months, weeks, days, 0, 0, 0, 0, 0, 0);
-    const optionsCopy = ObjectAssign(ObjectCreate(null), options);
+    const optionsCopy = ObjectCreate(null);
+    ES.CopyDataProperties(optionsCopy, options, []);
     const addedDate = ES.CalendarDateAdd(calendar, startDate, durationToAdd, options);
     const addedDateFields = ES.PrepareTemporalFields(addedDate, fieldNames, []);
 

polyfill/package.json

@@ -63,6 +63,7 @@
   ],
   "dependencies": {
     "big-integer": "^1.6.51",
+    "call-bind": "^1.0.2",
     "es-abstract": "^1.20.4"
   },
   "devDependencies": {
@@ -81,6 +82,7 @@
     "js-yaml": "^4.1.0",
     "progress": "^2.0.3",
     "rollup": "^2.68.0",
+    "rollup-plugin-node-polyfills": "^0.2.1",
     "rollup-plugin-terser": "^7.0.2",
     "tiny-glob": "^0.2.9"
   },

polyfill/rollup.config.js

@@ -1,4 +1,5 @@
 import commonjs from '@rollup/plugin-commonjs';
+import nodePolyfills from 'rollup-plugin-node-polyfills';
 import resolve from '@rollup/plugin-node-resolve';
 import babel from '@rollup/plugin-babel';
 import replace from '@rollup/plugin-replace';
@@ -27,6 +28,7 @@ export default [
     plugins: [
       replace({ ...replaceConfig, __debug__: false, __isTest262__: isTest262 }),
       commonjs(),
+      nodePolyfills(),
       resolve(resolveConfig)
     ],
     output: {
@@ -47,6 +49,7 @@ export default [
     plugins: [
       replace({ ...replaceConfig, __debug__: true, __isTest262__: false }),
       commonjs(),
+      nodePolyfills(),
       resolve(resolveConfig),
       babel(babelConfig)
     ]

spec/abstractops.html

@@ -505,28 +505,6 @@ <h1>LargerOfTwoTemporalUnits ( _u1_, _u2_ )</h1>
     </emu-alg>
   </emu-clause>
 
-  <emu-clause id="sec-temporal-mergelargestunitoption" type="abstract operation">
-    <h1>
-      MergeLargestUnitOption (
-        _options_: an Object,
-        _largestUnit_: a String,
-      ): either a normal completion containing an Object, or an abrupt completion
-    </h1>
-    <dl class="header">
-      <dt>description</dt>
-      <dd>It returns a new null-prototype Object with enumerable own String properties copied from the _options_ Object, and the `largestUnit` property set to _largestUnit_.</dd>
-    </dl>
-    <emu-alg>
-      1. Let _merged_ be OrdinaryObjectCreate(*null*).
-      1. Let _keys_ be ? EnumerableOwnProperties(_options_, ~key~).
-      1. For each element _nextKey_ of _keys_, do
-        1. Let _propValue_ be ? Get(_options_, _nextKey_).
-        1. Perform ! CreateDataPropertyOrThrow(_merged_, _nextKey_, _propValue_).
-      1. Perform ! CreateDataPropertyOrThrow(_merged_, *"largestUnit"*, _largestUnit_).
-      1. Return _merged_.
-    </emu-alg>
-  </emu-clause>
-
   <emu-clause id="sec-temporal-maximumtemporaldurationroundingincrement" aoid="MaximumTemporalDurationRoundingIncrement">
     <h1>MaximumTemporalDurationRoundingIncrement ( _unit_ )</h1>
     <emu-alg>

spec/calendar.html

@@ -723,24 +723,14 @@ <h1>
       </dl>
       <emu-alg>
         1. Let _merged_ be OrdinaryObjectCreate(%Object.prototype%).
-        1. Let _fieldsKeys_ be ? EnumerableOwnProperties(_fields_, ~key~).
-        1. For each element _key_ of _fieldsKeys_, do
-          1. If _key_ is not *"month"* or *"monthCode"*, then
-            1. Let _propValue_ be ? Get(_fields_, _key_).
-            1. If _propValue_ is not *undefined*, then
-              1. Perform ! CreateDataPropertyOrThrow(_merged_, _key_, _propValue_).
-        1. Let _additionalFieldsKeys_ be ? EnumerableOwnProperties(_additionalFields_, ~key~).
-        1. For each element _key_ of _additionalFieldsKeys_, do
-          1. Let _propValue_ be ? Get(_additionalFields_, _key_).
-          1. If _propValue_ is not *undefined*, then
-            1. Perform ! CreateDataPropertyOrThrow(_merged_, _key_, _propValue_).
-        1. If _additionalFieldsKeys_ does not contain either *"month"* or *"monthCode"*, then
-          1. Let _month_ be ? Get(_fields_, *"month"*).
-          1. If _month_ is not *undefined*, then
-            1. Perform ! CreateDataPropertyOrThrow(_merged_, *"month"*, _month_).
-          1. Let _monthCode_ be ? Get(_fields_, *"monthCode"*).
-          1. If _monthCode_ is not *undefined*, then
-            1. Perform ! CreateDataPropertyOrThrow(_merged_, *"monthCode"*, _monthCode_).
+        1. Perform ? CopyDataProperties(_merged_, _fields_, « », « *undefined* »).
+        1. Let _additionalFieldsCopy_ be OrdinaryObjectCreate(*null*).
+        1. Perform ? CopyDataProperties(_additionalFieldsCopy_, _additionalFields_, « », « *undefined* »).
+        1. NOTE: Every property of _additionalFieldsCopy_ is a data property with non-*undefined* value, but some property keys may be Symbols.
+        1. If ! _additionalFieldsCopy_.[[OwnPropertyKeys]]() contains *"month"* or *"monthCode"*, then
+          1. Perform ! DeletePropertyOrThrow(_merged_, *"month"*).
+          1. Perform ! DeletePropertyOrThrow(_merged_, *"monthCode"*).
+        1. Perform ? CopyDataProperties(_merged_, _additionalFieldsCopy_, « »).
         1. Return _merged_.
       </emu-alg>
     </emu-clause>

spec/intl.html

@@ -2076,17 +2076,9 @@ <h1>Temporal.Calendar.prototype.mergeFields ( _fields_, _additionalFields_ )</h1
             1. If _calendar_.[[Identifier]] is *"iso8601"*, then
               1. Return ? DefaultMergeCalendarFields(_fields_, _additionalFields_).
             1. Let _fieldsCopy_ be OrdinaryObjectCreate(%Object.prototype%).
-            1. Let _fieldsKeys_ be ? EnumerableOwnProperties(_fields_, ~key~).
-            1. For each element _key_ of _fieldsKeys_, do
-              1. Let _propValue_ be ? Get(_fields_, _key_).
-              1. If _propValue_ is not *undefined*, then
-                1. Perform ! CreateDataPropertyOrThrow(_fieldsCopy_, _key_, _propValue_).
+            1. Perform ? CopyDataProperties(_fieldsCopy_, _fields_, « », « *undefined* »).
             1. Let _additionalFieldsCopy_ be OrdinaryObjectCreate(%Object.prototype%).
-            1. Let _additionalFieldsKeys_ be ? EnumerableOwnProperties(_additionalFields_, ~key~).
-            1. For each element _key_ of _additionalFieldsKeys_, do
-              1. Let _propValue_ be ? Get(_additionalFields_, _key_).
-              1. If _propValue_ is not *undefined*, then
-                1. Perform ! CreateDataPropertyOrThrow(_additionalFieldsCopy_, _key_, _propValue_).
+            1. Perform ? CopyDataProperties(_additionalFieldsCopy_, _additionalFields_, « », « *undefined* »).
             1. Return CalendarDateMergeFields(_calendar_.[[Identifier]], _fieldsCopy_, _additionalFieldsCopy_).
           </emu-alg>
         </emu-clause>

spec/mainadditions.html

@@ -70,6 +70,43 @@ <h1>Mathematical Operations</h1>
     <p>[...]</p>
   </emu-clause>
 
+  <emu-clause id="sec-copydataproperties" type="abstract operation">
+    <h1>
+      CopyDataProperties (
+        _target_: an Object,
+        _source_: an ECMAScript language value,
+        <del>_excludedItems_: a List of property keys,</del>
+        <ins>_excludedKeys_: a List of property keys,</ins>
+        <ins>optional _excludedValues_: a List of ECMAScript language values,</ins>
+      ): either a normal completion containing ~unused~ or a throw completion
+    </h1>
+    <dl class="header">
+    </dl>
+    <emu-alg>
+      1. If _source_ is *undefined* or *null*, return ~unused~.
+      1. Let _from_ be ! ToObject(_source_).
+      1. Let _keys_ be ? <emu-meta effects="user-code">_from_.[[OwnPropertyKeys]]</emu-meta>().
+      1. For each element _nextKey_ of _keys_, do
+        1. Let _excluded_ be *false*.
+        1. For each element _e_ of <del>_excludedItems_</del><ins>_excludedKeys_</ins>, do
+          1. If SameValue(_e_, _nextKey_) is *true*, then
+            1. Set _excluded_ to *true*.
+        1. If _excluded_ is *false*, then
+          1. Let _desc_ be ? <emu-meta effects="user-code">_from_.[[GetOwnProperty]]</emu-meta>(_nextKey_).
+          1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
+            1. Let _propValue_ be ? Get(_from_, _nextKey_).
+            1. <ins>If _excludedValues_ is present, then</ins>
+              1. <ins>For each element _e_ of _excludedValues_, do</ins>
+                1. <ins>If SameValue(_e_, _propValue_) is *true*, then</ins>
+                  1. <ins>Set _excluded_ to *true*.</ins>
+            1. <del>Perform</del><ins>If _excluded_ is *false*, perform</ins> ! CreateDataPropertyOrThrow(_target_, _nextKey_, _propValue_).
+      1. Return ~unused~.
+    </emu-alg>
+    <emu-note>
+      <p>The target passed in here is always a newly created object which is not directly accessible in case of an error being thrown.</p>
+    </emu-note>
+  </emu-clause>
+
   <emu-clause id="sec-temporal-properties-of-the-legacy-date-prototype-object">
     <h1><a href="https://tc39.es/ecma262/#sec-properties-of-the-date-prototype-object">Properties of the Date Prototype Object</a></h1>
 

spec/plaindate.html

@@ -940,7 +940,9 @@ <h1>
         1. Set _other_ to ? ToTemporalDate(_other_).
         1. If ? CalendarEquals(_temporalDate_.[[Calendar]], _other_.[[Calendar]]) is *false*, throw a *RangeError* exception.
         1. Let _settings_ be ? GetDifferenceSettings(_operation_, _options_, ~date~, &laquo; &raquo;, *"day"*, *"day"*).
-        1. Let _untilOptions_ be ? MergeLargestUnitOption(_settings_.[[Options]], _settings_.[[LargestUnit]]).
+        1. Let _untilOptions_ be OrdinaryObjectCreate(*null*).
+        1. Perform ? CopyDataProperties(_untilOptions_, _settings_.[[Options]], « »).
+        1. Perform ! CreateDataPropertyOrThrow(_untilOptions_, *"largestUnit"*, _settings_.[[LargestUnit]]).
         1. Let _result_ be ? CalendarDateUntil(_temporalDate_.[[Calendar]], _temporalDate_, _other_, _untilOptions_).
         1. If _settings_.[[SmallestUnit]] is not *"day"* or _settings_.[[RoundingIncrement]] &ne; 1, then
           1. Set _result_ to (? RoundDuration(_result_.[[Years]], _result_.[[Months]], _result_.[[Weeks]], _result_.[[Days]], 0, 0, 0, 0, 0, 0, _settings_.[[RoundingIncrement]], _settings_.[[SmallestUnit]], _settings_.[[RoundingMode]], _temporalDate_)).[[DurationRecord]].