docs: Adds documentation for generic type argument to SimpleChanges

Author: SkyZeroZx

adev/src/content/guide/components/lifecycle.md

@@ -108,19 +108,20 @@ mapping each component input name to a `SimpleChange` object. Each `SimpleChange
 input's previous value, its current value, and a flag for whether this is the first time the input
 has changed.
 
+You can optionally pass the current class or this as the first generic argument for stronger type checking.
+
 ```ts
 @Component({
   /* ... */
 })
 export class UserProfile {
   name = input('');
 
-  ngOnChanges(changes: SimpleChanges) {
-    for (const inputName in changes) {
-      const inputValues = changes[inputName];
-      console.log(`Previous ${inputName} == ${inputValues.previousValue}`);
-      console.log(`Current ${inputName} == ${inputValues.currentValue}`);
-      console.log(`Is first ${inputName} change == ${inputValues.firstChange}`);
+  ngOnChanges(changes: SimpleChanges<UserProfile>) {
+    if (changes.name) {
+      console.log(`Previous: ${changes.name.previousValue}`);
+      console.log(`Current: ${changes.name.currentValue}`);
+      console.log(`Is first ${changes.name.firstChange}`);
     }
   }
 }

packages/core/src/change_detection/simple_change.ts

@@ -39,6 +39,8 @@ export class SimpleChange<T = any> {
  *
  * @see {@link OnChanges}
  *
+ * @see [Inspecting changes](guide/components/lifecycle#inspecting-changes)
+ *
  * @publicApi
  */
 export type SimpleChanges<T = unknown> = T extends object