From 9f0c549bc8916897d16fb35cc8a3e8b98d5f8cf1 Mon Sep 17 00:00:00 2001
From: Pawel Kozlowski <pkozlowski.opensource@gmail.com>
Date: Fri, 4 Oct 2019 12:13:25 +0200
Subject: [PATCH] perf(ivy): avoid memory allocation in the isAnimationProp
 check (#32997)

Accessing a string's character at index allocates a new, single character string.
A better (faster) check is to use `charCodeAt` that doesn't trigger allocation.

This simple change speeds up the element_text_create benchmark by ~7%.

PR Close #32997
---
 packages/core/src/render3/instructions/shared.ts           | 5 ++---
 packages/core/src/render3/util/attrs_utils.ts              | 7 ++++---
 .../test/bundling/cyclic_import/bundle.golden_symbols.json | 3 ---
 .../core/test/bundling/todo/bundle.golden_symbols.json     | 3 ---
 4 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/packages/core/src/render3/instructions/shared.ts b/packages/core/src/render3/instructions/shared.ts
index c4706c9a54..0b9d24a3ce 100644
--- a/packages/core/src/render3/instructions/shared.ts
+++ b/packages/core/src/render3/instructions/shared.ts
@@ -33,7 +33,7 @@ import {isNodeMatchingSelectorList} from '../node_selector_matcher';
 import {ActiveElementFlags, executeElementExitFn, getBindingsEnabled, getCheckNoChangesMode, getIsParent, getPreviousOrParentTNode, getSelectedIndex, hasActiveElementFlag, incrementActiveDirectiveId, namespaceHTMLInternal, selectView, setActiveHostElement, setBindingRoot, setCheckNoChangesMode, setCurrentDirectiveDef, setCurrentQueryIndex, setPreviousOrParentTNode, setSelectedIndex} from '../state';
 import {renderStylingMap} from '../styling/bindings';
 import {NO_CHANGE} from '../tokens';
-import {ANIMATION_PROP_PREFIX, isAnimationProp} from '../util/attrs_utils';
+import {isAnimationProp} from '../util/attrs_utils';
 import {INTERPOLATION_DELIMITER, renderStringify, stringifyForError} from '../util/misc_utils';
 import {getLViewParent} from '../util/view_traversal_utils';
 import {getComponentViewByIndex, getNativeByIndex, getNativeByTNode, getTNode, isCreationMode, readPatchedLView, resetPreOrderHookFlags, unwrapRNode, viewAttachedToChangeDetector} from '../util/view_utils';
@@ -980,8 +980,7 @@ function validateProperty(
   // The property is considered valid if the element matches the schema, it exists on the element
   // or it is synthetic, and we are in a browser context (web worker nodes should be skipped).
   return matchingSchemas(hostView, tNode.tagName) || propName in element ||
-      propName[0] === ANIMATION_PROP_PREFIX || typeof Node !== 'function' ||
-      !(element instanceof Node);
+      isAnimationProp(propName) || typeof Node !== 'function' || !(element instanceof Node);
 }
 
 function matchingSchemas(hostView: LView, tagName: string | null): boolean {
diff --git a/packages/core/src/render3/util/attrs_utils.ts b/packages/core/src/render3/util/attrs_utils.ts
index 6249d6adf9..5d729c2c76 100644
--- a/packages/core/src/render3/util/attrs_utils.ts
+++ b/packages/core/src/render3/util/attrs_utils.ts
@@ -100,8 +100,9 @@ export function isNameOnlyAttributeMarker(marker: string | AttributeMarker | Css
       marker === AttributeMarker.I18n;
 }
 
-export const ANIMATION_PROP_PREFIX = '@';
-
 export function isAnimationProp(name: string): boolean {
-  return name[0] === ANIMATION_PROP_PREFIX;
+  // Perf note: accessing charCodeAt to check for the first character of a string is faster as
+  // compared to accessing a character at index 0 (ex. name[0]). The main reason for this is that
+  // charCodeAt doesn't allocate memory to return a substring.
+  return name.charCodeAt(0) === 64;  // @
 }
diff --git a/packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json b/packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json
index 8c761c8140..06e787207c 100644
--- a/packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json
+++ b/packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json
@@ -2,9 +2,6 @@
   {
     "name": "ACTIVE_INDEX"
   },
-  {
-    "name": "ANIMATION_PROP_PREFIX"
-  },
   {
     "name": "BINDING_INDEX"
   },
diff --git a/packages/core/test/bundling/todo/bundle.golden_symbols.json b/packages/core/test/bundling/todo/bundle.golden_symbols.json
index b7a2012325..bb63b82b26 100644
--- a/packages/core/test/bundling/todo/bundle.golden_symbols.json
+++ b/packages/core/test/bundling/todo/bundle.golden_symbols.json
@@ -2,9 +2,6 @@
   {
     "name": "ACTIVE_INDEX"
   },
-  {
-    "name": "ANIMATION_PROP_PREFIX"
-  },
   {
     "name": "BINDING_INDEX"
   },