refactor(core): remove looseIdentical in favor of built-in Object.is (angular#37191)

atscott · matsko · commit 4456e7e4dec8 · 2020-06-01T17:19:17.000-04:00
Remove `looseIdentical` implementation and instead use the ES2015 `Object.is` in its place. They behave exactly the same way except for `+0`/`-0`. `looseIdentical(+0, -0)` => `true` `Object.is(+0, -0)` => `false` Other than the difference noted above, this is not be a breaking change because: 1. `looseIdentical` is a private API 2. ES2015 is listed as a mandatory polyfill in the [browser support guide](https://angular.io/guide/browser-support#mandatory-polyfills) 3. Also note that `Ivy` already uses `Object.is` in `bindingUpdated`. PR Close angular#37191
diff --git a/packages/core/src/change_detection/change_detection_util.ts b/packages/core/src/change_detection/change_detection_util.ts
@@ -6,7 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {looseIdentical} from '../util/comparison';
 import {getSymbolIterator} from '../util/symbol';
 
 export function devModeEqual(a: any, b: any): boolean {
@@ -20,7 +19,7 @@ export function devModeEqual(a: any, b: any): boolean {
     if (!isListLikeIterableA && isAObject && !isListLikeIterableB && isBObject) {
       return true;
     } else {
-      return looseIdentical(a, b);
+      return Object.is(a, b);
     }
   }
 }
diff --git a/packages/core/src/change_detection/differs/default_iterable_differ.ts b/packages/core/src/change_detection/differs/default_iterable_differ.ts
@@ -6,7 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {looseIdentical} from '../../util/comparison';
 import {stringify} from '../../util/stringify';
 import {isListLikeIterable, iterateListLike} from '../change_detection_util';
 
@@ -180,15 +179,15 @@ export class DefaultIterableDiffer<V> implements IterableDiffer<V>, IterableChan
       for (let index = 0; index < this.length; index++) {
         item = collection[index];
         itemTrackBy = this._trackByFn(index, item);
-        if (record === null || !looseIdentical(record.trackById, itemTrackBy)) {
+        if (record === null || !Object.is(record.trackById, itemTrackBy)) {
           record = this._mismatch(record, item, itemTrackBy, index);
           mayBeDirty = true;
         } else {
           if (mayBeDirty) {
             // TODO(misko): can we limit this to duplicates only?
             record = this._verifyReinsertion(record, item, itemTrackBy, index);
           }
-          if (!looseIdentical(record.item, item)) this._addIdentityChange(record, item);
+          if (!Object.is(record.item, item)) this._addIdentityChange(record, item);
         }
 
         record = record._next;
@@ -197,15 +196,15 @@ export class DefaultIterableDiffer<V> implements IterableDiffer<V>, IterableChan
       index = 0;
       iterateListLike(collection, (item: V) => {
         itemTrackBy = this._trackByFn(index, item);
-        if (record === null || !looseIdentical(record.trackById, itemTrackBy)) {
+        if (record === null || !Object.is(record.trackById, itemTrackBy)) {
           record = this._mismatch(record, item, itemTrackBy, index);
           mayBeDirty = true;
         } else {
           if (mayBeDirty) {
             // TODO(misko): can we limit this to duplicates only?
             record = this._verifyReinsertion(record, item, itemTrackBy, index);
           }
-          if (!looseIdentical(record.item, item)) this._addIdentityChange(record, item);
+          if (!Object.is(record.item, item)) this._addIdentityChange(record, item);
         }
         record = record._next;
         index++;
@@ -289,7 +288,7 @@ export class DefaultIterableDiffer<V> implements IterableDiffer<V>, IterableChan
     if (record !== null) {
       // We have seen this before, we need to move it forward in the collection.
       // But first we need to check if identity changed, so we can update in view if necessary
-      if (!looseIdentical(record.item, item)) this._addIdentityChange(record, item);
+      if (!Object.is(record.item, item)) this._addIdentityChange(record, item);
 
       this._moveAfter(record, previousRecord, index);
     } else {
@@ -298,7 +297,7 @@ export class DefaultIterableDiffer<V> implements IterableDiffer<V>, IterableChan
       if (record !== null) {
         // It is an item which we have evicted earlier: reinsert it back into the list.
         // But first we need to check if identity changed, so we can update in view if necessary
-        if (!looseIdentical(record.item, item)) this._addIdentityChange(record, item);
+        if (!Object.is(record.item, item)) this._addIdentityChange(record, item);
 
         this._reinsertAfter(record, previousRecord, index);
       } else {
@@ -628,7 +627,7 @@ class _DuplicateItemRecordList<V> {
     let record: IterableChangeRecord_<V>|null;
     for (record = this._head; record !== null; record = record._nextDup) {
       if ((atOrAfterIndex === null || atOrAfterIndex <= record.currentIndex!) &&
-          looseIdentical(record.trackById, trackById)) {
+          Object.is(record.trackById, trackById)) {
         return record;
       }
     }
diff --git a/packages/core/src/change_detection/differs/default_keyvalue_differ.ts b/packages/core/src/change_detection/differs/default_keyvalue_differ.ts
@@ -6,7 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {looseIdentical} from '../../util/comparison';
 import {stringify} from '../../util/stringify';
 import {isJsObject} from '../change_detection_util';
 import {KeyValueChangeRecord, KeyValueChanges, KeyValueDiffer, KeyValueDifferFactory} from './keyvalue_differs';
@@ -229,7 +228,7 @@ export class DefaultKeyValueDiffer<K, V> implements KeyValueDiffer<K, V>, KeyVal
 
   // Add the record or a given key to the list of changes only when the value has actually changed
   private _maybeAddToChanges(record: KeyValueChangeRecord_<K, V>, newValue: any): void {
-    if (!looseIdentical(newValue, record.currentValue)) {
+    if (!Object.is(newValue, record.currentValue)) {
       record.previousValue = record.currentValue;
       record.currentValue = newValue;
       this._addToChanges(record);
diff --git a/packages/core/src/core_private_export.ts b/packages/core/src/core_private_export.ts
@@ -27,7 +27,6 @@ export {GetterFn as ɵGetterFn, MethodFn as ɵMethodFn, SetterFn as ɵSetterFn}
 export {allowSanitizationBypassAndThrow as ɵallowSanitizationBypassAndThrow, BypassType as ɵBypassType, getSanitizationBypassType as ɵgetSanitizationBypassType, SafeHtml as ɵSafeHtml, SafeResourceUrl as ɵSafeResourceUrl, SafeScript as ɵSafeScript, SafeStyle as ɵSafeStyle, SafeUrl as ɵSafeUrl, SafeValue as ɵSafeValue, unwrapSafeValue as ɵunwrapSafeValue} from './sanitization/bypass';
 export {_sanitizeHtml as ɵ_sanitizeHtml} from './sanitization/html_sanitizer';
 export {_sanitizeUrl as ɵ_sanitizeUrl} from './sanitization/url_sanitizer';
-export {looseIdentical as ɵlooseIdentical,} from './util/comparison';
 export {makeDecorator as ɵmakeDecorator} from './util/decorators';
 export {global as ɵglobal} from './util/global';
 export {isObservable as ɵisObservable, isPromise as ɵisPromise} from './util/lang';
diff --git a/packages/core/src/util/comparison.ts b/packages/core/src/util/comparison.ts
@@ -8,12 +8,6 @@
 
 import {areIterablesEqual, isListLikeIterable} from './iterable';
 
-
-// JS has NaN !== NaN
-export function looseIdentical(a: any, b: any): boolean {
-  return a === b || typeof a === 'number' && typeof b === 'number' && isNaN(a) && isNaN(b);
-}
-
 export function devModeEqual(a: any, b: any): boolean {
   const isListLikeIterableA = isListLikeIterable(a);
   const isListLikeIterableB = isListLikeIterable(b);
@@ -25,7 +19,7 @@ export function devModeEqual(a: any, b: any): boolean {
     if (!isListLikeIterableA && isAObject && !isListLikeIterableB && isBObject) {
       return true;
     } else {
-      return looseIdentical(a, b);
+      return Object.is(a, b);
     }
   }
 }
diff --git a/packages/core/src/view/util.ts b/packages/core/src/view/util.ts
@@ -10,7 +10,6 @@ import {devModeEqual, WrappedValue} from '../change_detection/change_detection';
 import {SOURCE} from '../di/injector_compatibility';
 import {ViewEncapsulation} from '../metadata/view';
 import {RendererType2} from '../render/api';
-import {looseIdentical} from '../util/comparison';
 import {stringify} from '../util/stringify';
 
 import {expressionChangedAfterItHasBeenCheckedError} from './errors';
@@ -81,7 +80,7 @@ export function checkBinding(
     view: ViewData, def: NodeDef, bindingIdx: number, value: any): boolean {
   const oldValues = view.oldValues;
   if ((view.state & ViewState.FirstCheck) ||
-      !looseIdentical(oldValues[def.bindingIndex + bindingIdx], value)) {
+      !Object.is(oldValues[def.bindingIndex + bindingIdx], value)) {
     return true;
   }
   return false;
diff --git a/packages/core/test/bundling/todo/bundle.golden_symbols.json b/packages/core/test/bundling/todo/bundle.golden_symbols.json
@@ -941,9 +941,6 @@
   {
     "name": "locateHostElement"
   },
-  {
-    "name": "looseIdentical"
-  },
   {
     "name": "makeMetadataCtor"
   },
diff --git a/packages/core/test/change_detection/util.ts b/packages/core/test/change_detection/util.ts
@@ -9,7 +9,6 @@
 import {IterableChangeRecord, IterableChanges} from '@angular/core/src/change_detection/differs/iterable_differs';
 import {KeyValueChangeRecord, KeyValueChanges} from '@angular/core/src/change_detection/differs/keyvalue_differs';
 
-import {looseIdentical} from '../../src/util/comparison';
 import {stringify} from '../../src/util/stringify';
 
 export function iterableDifferToString<V>(iterableChanges: IterableChanges<V>) {
@@ -64,7 +63,7 @@ export function iterableChangesAsString({
 }
 
 function kvcrAsString(kvcr: KeyValueChangeRecord<string, any>) {
-  return looseIdentical(kvcr.previousValue, kvcr.currentValue) ?
+  return Object.is(kvcr.previousValue, kvcr.currentValue) ?
       stringify(kvcr.key) :
       (stringify(kvcr.key) + '[' + stringify(kvcr.previousValue) + '->' +
        stringify(kvcr.currentValue) + ']');
diff --git a/packages/forms/src/directives/select_control_value_accessor.ts b/packages/forms/src/directives/select_control_value_accessor.ts
@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Directive, ElementRef, forwardRef, Host, Input, OnDestroy, Optional, Renderer2, StaticProvider, ɵlooseIdentical as looseIdentical} from '@angular/core';
+import {Directive, ElementRef, forwardRef, Host, Input, OnDestroy, Optional, Renderer2, StaticProvider} from '@angular/core';
 
 import {ControlValueAccessor, NG_VALUE_ACCESSOR} from './control_value_accessor';
 
@@ -121,7 +121,7 @@ export class SelectControlValueAccessor implements ControlValueAccessor {
     this._compareWith = fn;
   }
 
-  private _compareWith: (o1: any, o2: any) => boolean = looseIdentical;
+  private _compareWith: (o1: any, o2: any) => boolean = Object.is;
 
   constructor(private _renderer: Renderer2, private _elementRef: ElementRef) {}
 
diff --git a/packages/forms/src/directives/select_multiple_control_value_accessor.ts b/packages/forms/src/directives/select_multiple_control_value_accessor.ts
@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Directive, ElementRef, forwardRef, Host, Input, OnDestroy, Optional, Renderer2, StaticProvider, ɵlooseIdentical as looseIdentical} from '@angular/core';
+import {Directive, ElementRef, forwardRef, Host, Input, OnDestroy, Optional, Renderer2, StaticProvider} from '@angular/core';
 
 import {ControlValueAccessor, NG_VALUE_ACCESSOR} from './control_value_accessor';
 
@@ -118,7 +118,7 @@ export class SelectMultipleControlValueAccessor implements ControlValueAccessor
     this._compareWith = fn;
   }
 
-  private _compareWith: (o1: any, o2: any) => boolean = looseIdentical;
+  private _compareWith: (o1: any, o2: any) => boolean = Object.is;
 
   constructor(private _renderer: Renderer2, private _elementRef: ElementRef) {}
 
diff --git a/packages/forms/src/directives/shared.ts b/packages/forms/src/directives/shared.ts
@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {isDevMode, ɵlooseIdentical as looseIdentical} from '@angular/core';
+import {isDevMode} from '@angular/core';
 
 import {FormArray, FormControl, FormGroup} from '../model';
 import {Validators} from '../validators';
@@ -156,7 +156,7 @@ export function isPropertyUpdated(changes: {[key: string]: any}, viewModel: any)
   const change = changes['model'];
 
   if (change.isFirstChange()) return true;
-  return !looseIdentical(viewModel, change.currentValue);
+  return !Object.is(viewModel, change.currentValue);
 }
 
 const BUILTIN_ACCESSORS = [
diff --git a/packages/upgrade/static/src/upgrade_component.ts b/packages/upgrade/static/src/upgrade_component.ts
@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Directive, DoCheck, ElementRef, EventEmitter, Injector, OnChanges, OnDestroy, OnInit, SimpleChanges, ɵlooseIdentical as looseIdentical} from '@angular/core';
+import {Directive, DoCheck, ElementRef, EventEmitter, Injector, OnChanges, OnDestroy, OnInit, SimpleChanges} from '@angular/core';
 
 import {IAttributes, IAugmentedJQuery, IDirective, IInjectorService, ILinkFn, IScope, ITranscludeFunction} from '../../src/common/src/angular1';
 import {$SCOPE} from '../../src/common/src/constants';
@@ -206,7 +206,7 @@ export class UpgradeComponent implements OnInit, OnChanges, DoCheck, OnDestroy {
       const newValue = this.bindingDestination[propName];
       const oldValue = twoWayBoundLastValues[idx];
 
-      if (!looseIdentical(newValue, oldValue)) {
+      if (!Object.is(newValue, oldValue)) {
         const outputName = propertyToOutputMap[propName];
         const eventEmitter: EventEmitter<any> = (this as any)[outputName];
 

Original file line number	Diff line number	Diff line change
`@@ -6,7 +6,6 @@`
`6`	`6`	`* found in the LICENSE file at https://angular.io/license`
`7`	`7`	`*/`
`8`	`8`
`9`		`-import {looseIdentical} from '../util/comparison';`
`10`	`9`	`import {getSymbolIterator} from '../util/symbol';`
`11`	`10`
`12`	`11`	`export function devModeEqual(a: any, b: any): boolean {`
`@@ -20,7 +19,7 @@ export function devModeEqual(a: any, b: any): boolean {`
`20`	`19`	`if (!isListLikeIterableA && isAObject && !isListLikeIterableB && isBObject) {`
`21`	`20`	`return true;`
`22`	`21`	`} else {`
`23`		`- return looseIdentical(a, b);`
	`22`	`+ return Object.is(a, b);`
`24`	`23`	`}`
`25`	`24`	`}`
`26`	`25`	`}`
Original file line number	Diff line number	Diff line change
`@@ -8,12 +8,6 @@`
`8`	`8`
`9`	`9`	`import {areIterablesEqual, isListLikeIterable} from './iterable';`
`10`	`10`
`11`		`-`
`12`		`-// JS has NaN !== NaN`
`13`		`-export function looseIdentical(a: any, b: any): boolean {`
`14`		`- return a === b \|\| typeof a === 'number' && typeof b === 'number' && isNaN(a) && isNaN(b);`
`15`		`-}`
`16`		`-`
`17`	`11`	`export function devModeEqual(a: any, b: any): boolean {`
`18`	`12`	`const isListLikeIterableA = isListLikeIterable(a);`
`19`	`13`	`const isListLikeIterableB = isListLikeIterable(b);`
`@@ -25,7 +19,7 @@ export function devModeEqual(a: any, b: any): boolean {`
`25`	`19`	`if (!isListLikeIterableA && isAObject && !isListLikeIterableB && isBObject) {`
`26`	`20`	`return true;`
`27`	`21`	`} else {`
`28`		`- return looseIdentical(a, b);`
	`22`	`+ return Object.is(a, b);`
`29`	`23`	`}`
`30`	`24`	`}`
`31`	`25`	`}`
Original file line number	Diff line number	Diff line change
`@@ -941,9 +941,6 @@`
`941`	`941`	`{`
`942`	`942`	`"name": "locateHostElement"`
`943`	`943`	`},`
`944`		`- {`
`945`		`- "name": "looseIdentical"`
`946`		`- },`
`947`	`944`	`{`
`948`	`945`	`"name": "makeMetadataCtor"`
`949`	`946`	`},`