From eb9eebbb45352da6000560ee0988d9d59dce1254 Mon Sep 17 00:00:00 2001
From: George Kalpakas <kalpakas.g@gmail.com>
Date: Wed, 14 Oct 2020 16:57:00 +0300
Subject: [PATCH] refactor(elements): simplify code after IE<11 support removal
 (#39265)

Support for IE<11 is being removed in v11. PR #39090 removed some code
that was no longer needed.

Now that there are no longer multiple code-paths (which was previously
needed for IE<11 support), this commit simplifies the code further (for
example, to avoid unnecessary functions calls and to avoid iterating
over a component's inputs multiple times).

PR Close #39265
---
 .../elements/src/create-custom-element.ts     | 36 ++++++++-----------
 1 file changed, 15 insertions(+), 21 deletions(-)

diff --git a/packages/elements/src/create-custom-element.ts b/packages/elements/src/create-custom-element.ts
index ffe0f00409..3198d07f79 100644
--- a/packages/elements/src/create-custom-element.ts
+++ b/packages/elements/src/create-custom-element.ts
@@ -151,18 +151,19 @@ export function createCustomElement<P>(
         const strategy = this._ngElementStrategy =
             strategyFactory.create(this.injector || config.injector);
 
-        // Collect pre-existing values on the element to re-apply through the strategy.
-        const preExistingValues =
-            inputs.filter(({propName}) => this.hasOwnProperty(propName)).map(({propName}): [
-              string, any
-            ] => [propName, (this as any)[propName]]);
+        // Re-apply pre-existing input values (set as properties on the element) through the
+        // strategy.
+        inputs.forEach(({propName}) => {
+          if (!this.hasOwnProperty(propName)) {
+            // No pre-existing value for `propName`.
+            return;
+          }
 
-        // Delete the property from the instance, so that it can go through the getters/setters
-        // set on `NgElementImpl.prototype`.
-        preExistingValues.forEach(([propName]) => delete (this as any)[propName]);
-
-        // Re-apply pre-existing values through the strategy.
-        preExistingValues.forEach(([propName, value]) => strategy.setInputValue(propName, value));
+          // Delete the property from the instance and re-apply it through the strategy.
+          const value = (this as any)[propName];
+          delete (this as any)[propName];
+          strategy.setInputValue(propName, value);
+        });
       }
 
       return this._ngElementStrategy!;
@@ -229,17 +230,8 @@ export function createCustomElement<P>(
   }
 
   // Add getters and setters to the prototype for each property input.
-  defineInputGettersSetters(inputs, NgElementImpl.prototype);
-
-  return (NgElementImpl as any) as NgElementConstructor<P>;
-}
-
-// Helpers
-function defineInputGettersSetters(
-    inputs: {propName: string, templateName: string}[], target: object): void {
-  // Add getters and setters for each property input.
   inputs.forEach(({propName}) => {
-    Object.defineProperty(target, propName, {
+    Object.defineProperty(NgElementImpl.prototype, propName, {
       get(): any {
         return this.ngElementStrategy.getInputValue(propName);
       },
@@ -250,4 +242,6 @@ function defineInputGettersSetters(
       enumerable: true,
     });
   });
+
+  return (NgElementImpl as any) as NgElementConstructor<P>;
 }