frint: Expose class methods on the app instance level (#431)

* Expose class methods on the app instance level

* Update documentation

* Fix linting errors

* Don't overwrite app fields with options methods

* Remove `app.getMethods` method

* Rename App index signature

packages/frint/README.md

@@ -275,6 +275,7 @@ The base App class.
 
 1. `options` (`Object`)
     * `options.name`: (`String` [required]): Name of your App.
+    * `options.methods`: (`Object` [optional]): Object with the methods your App exposes on the instance level.
     * `options.initialize`: (`Function` [optional]): Called when App is constructed.
     * `options.beforeDestroy`: (`Function` [optional]): Called when App is about to be destroyed.
     * `options.providers`: (`Array` [optional]): Array of provider objects.

packages/frint/src/App.spec.ts

@@ -13,14 +13,41 @@ describe('frint  › App', () => {
     }).to.throw(/Must provide `name` in options/);
   });
 
-  it('gets option value', () => {
+  it('gets name option value', () => {
     const app = new App({
       name: 'MyApp',
     });
 
     expect(app.getName()).to.equal('MyApp');
   });
 
+  it('exposes methods as class properties', () => {
+    const methods = {
+      foo() { return 'foo'; },
+    };
+
+    const app = new App({
+      name: 'MyApp',
+      methods,
+    });
+
+    expect(app.foo()).to.equal('foo');
+  });
+
+  it('does not overwrite app properties or methods with options methods', () => {
+    const methods = {
+      // tslint:disable-next-line:no-empty
+      getName() {},
+    };
+
+    expect(() => (
+      new App({
+        name: 'MyApp',
+        methods,
+      })
+    )).to.throw(/Cannot overwrite app's `getName` property or method with options method/);
+  });
+
   it('gets parent and root app', () => {
     const rootApp = new App({
       name: 'RootApp',

packages/frint/src/App.ts

@@ -32,6 +32,10 @@ function makeInstanceKey(region = null, regionKey = null, multi = false) {
   return key;
 }
 
+export interface Methods {
+  [key: string]: () => any;
+}
+
 export interface ProviderNames {
   component: string;
   container: string;
@@ -75,6 +79,7 @@ export interface AppRegistration {
 
 export interface AppOptions {
   name?: string;
+  methods?: Methods;
   parentApp?: App;
   providers?: FrintProvider[];
   providerNames?: ProviderNames;
@@ -88,6 +93,7 @@ export interface AppClass {
 }
 
 export class App {
+  [method: string]: any;
   public container: Container;
   private options: AppOptions;
   private _appsCollection: AppRegistration[];
@@ -96,6 +102,7 @@ export class App {
   constructor(opts: AppOptions) {
     this.options = {
       name: null,
+      methods: {},
       parentApp: null,
       providers: [],
 
@@ -116,6 +123,19 @@ export class App {
       throw new Error('Must provide `name` in options');
     }
 
+    // expose methods as class properties
+    Object.keys(this.options.methods).forEach(methodName => {
+      const method = this.options.methods[methodName];
+
+      if (typeof method === 'function') {
+        if (this[methodName] !== undefined) {
+          throw new Error(`Cannot overwrite app's \`${methodName}\` property or method with options method.`);
+        }
+
+        this[methodName] = method.bind(this);
+      }
+    });
+
     // children - create Observable if root
     this._appsCollection = [];
     this._apps$ = new BehaviorSubject(this._appsCollection);