Type improvements (#1746)

* Make array arguments immutable

Type the array component arguments as immutable. The component doesn't actually mutate them, so typing them as readonly allows caller to pass in either mutable or immutable arrays, rather than only mutable ones.

* Use Promise instead of PromiseProxy

A couple of things were typed as `PromiseProxy`s when they only used the `Promise` interface. This prevented callers from, for example, supplying a search function that produces a regular promise, i.e. a plain old async function. So change them to `Promise`.

The `@selected` argument still uses a `PromiseProxy` because the component observes its `content` property, so allowing it to be a `Promise` would be a more involved code change.

ember-power-select/src/components/power-select.ts

@@ -38,8 +38,8 @@ interface SelectActions extends DropdownActions {
 export interface Select extends Dropdown {
   selected: any;
   highlighted: any;
-  options: any[];
-  results: any[];
+  options: readonly any[];
+  results: readonly any[];
   resultsCount: number;
   loading: boolean;
   isActive: boolean;
@@ -66,7 +66,7 @@ export interface PowerSelectArgs {
   noMatchesMessageComponent?: string | ComponentLike<any>;
   matchTriggerWidth?: boolean;
   resultCountMessage?: (resultCount: number) => string;
-  options?: any[] | PromiseProxy<any[]>;
+  options?: readonly any[] | Promise<readonly any[]>;
   selected?: any | PromiseProxy<any>;
   destination?: string;
   closeOnSelect?: boolean;
@@ -114,7 +114,10 @@ export interface PowerSelectArgs {
   typeAheadOptionMatcher?: MatcherFn;
   buildSelection?: (selected: any, select: Select) => any;
   onChange: (selection: any, select: Select, event?: Event) => void;
-  search?: (term: string, select: Select) => any[] | PromiseProxy<any[]>;
+  search?: (
+    term: string,
+    select: Select,
+  ) => readonly any[] | Promise<readonly any[]>;
   onOpen?: (select: Select, e: Event) => boolean | undefined;
   onClose?: (select: Select, e: Event) => boolean | undefined;
   onInput?: (term: string, select: Select, e: Event) => string | false | void;
@@ -165,11 +168,11 @@ export default class PowerSelectComponent extends Component<PowerSelectSignature
   };
 
   // Tracked properties
-  @tracked private _resolvedOptions?: any[];
+  @tracked private _resolvedOptions?: readonly any[];
   @tracked private _resolvedSelected?: any;
   @tracked private _repeatingChar = '';
   @tracked private _expirableSearchText = '';
-  @tracked private _searchResult?: any[];
+  @tracked private _searchResult?: readonly any[];
   @tracked isActive = false;
   @tracked loading = false;
   @tracked searchText = '';
@@ -178,9 +181,11 @@ export default class PowerSelectComponent extends Component<PowerSelectSignature
   storedAPI!: Select;
 
   private _uid = guidFor(this);
-  private _lastOptionsPromise?: PromiseProxy<any[]>;
+  private _lastOptionsPromise?: Promise<readonly any[]>;
   private _lastSelectedPromise?: PromiseProxy<any>;
-  private _lastSearchPromise?: PromiseProxy<any[]> | CancellablePromise<any[]>;
+  private _lastSearchPromise?:
+    | Promise<readonly any[]>
+    | CancellablePromise<readonly any[]>;
   private _filterResultsCache: {
     results: any[];
     options: any[];
@@ -501,7 +506,7 @@ export default class PowerSelectComponent extends Component<PowerSelectSignature
     if (isPromiseLike(this.args.options)) {
       if (this._lastOptionsPromise === this.args.options) return; // promise is still the same
       const currentOptionsPromise = this.args.options;
-      this._lastOptionsPromise = currentOptionsPromise as PromiseProxy<any[]>;
+      this._lastOptionsPromise = currentOptionsPromise;
       this.loading = true;
       this._lastOptionsPromise
         .then((resolvedOptions) => {
@@ -791,7 +796,7 @@ export default class PowerSelectComponent extends Component<PowerSelectSignature
   }
 
   findWithOffset(
-    options: any[],
+    options: readonly any[],
     term: string,
     offset: number,
     skipDisabled = false,