fix: guard against the script bootstrapping twice on a page

src/index.ts

@@ -3,9 +3,9 @@ import './patch';
 import 'reflect-metadata';
 import 'regenerator-runtime/runtime';
 
-import DependencyContainer from 'tsyringe/dist/typings/types/dependency-container';
 import { bootstrap } from './bootstrap';
 import { container } from 'tsyringe';
+import { inject } from './inject';
 import { tw2patch } from './tw2-patch';
 import { TWCalcPublicApi } from './tw-calc.types';
 
@@ -14,34 +14,3 @@ container.register('localStorage', { useValue: localStorage });
 container.register('tw2patch', { useValue: tw2patch });
 
 inject<TWCalcPublicApi>(bootstrap, window, location);
-
-// inject script when the game is ready
-function inject<T>(
-    bootstrapper: (dependencyContainer: DependencyContainer) => T,
-    window: Window,
-    location: Location,
-): NodeJS.Timeout {
-    const injectInterval = setInterval(() => {
-        if (!isGameReady(window)) {
-            return;
-        }
-        // clear the injector interval
-        clearInterval(injectInterval);
-        // inject the script
-        window['TW_Calc'] = injectScript<T>(bootstrapper, location);
-    }, 250);
-    return injectInterval;
-}
-
-function isGameReady(window: Window): boolean {
-    // jquery must be loaded
-    return typeof window['$'] !== 'undefined';
-}
-
-function injectScript<T>(bootstrapper: (dependencyContainer: DependencyContainer) => T, location: Location): T {
-    const { href } = location;
-    if ((href.indexOf('.the-west.') != -1 || href.indexOf('.tw.innogames.') != -1) && href.indexOf('game.php') != -1) {
-        return bootstrapper(container);
-    }
-    throw new Error('TW-Calc must be loaded in the game!');
-}

src/inject.spec.ts

@@ -0,0 +1,55 @@
+import { inject, isAlreadyInjected, isGameReady } from './inject';
+
+describe('inject', () => {
+    let win: Partial<Window> & { $?: unknown; TW_Calc?: unknown };
+    let location: Location;
+    let bootstrapper: jasmine.Spy;
+
+    beforeEach(() => {
+        jasmine.clock().install();
+        bootstrapper = jasmine.createSpy('bootstrap').and.returnValue({});
+        location = { href: 'https://en.the-west.net/game.php' } as Location;
+        win = {};
+    });
+
+    afterEach(() => {
+        jasmine.clock().uninstall();
+    });
+
+    it('isGameReady reflects jQuery presence', () => {
+        expect(isGameReady({} as Window)).toBe(false);
+        expect(isGameReady({ $: () => undefined } as unknown as Window)).toBe(true);
+    });
+
+    it('isAlreadyInjected reflects TW_Calc presence', () => {
+        expect(isAlreadyInjected({} as Window)).toBe(false);
+        expect(isAlreadyInjected({ TW_Calc: {} } as unknown as Window)).toBe(true);
+    });
+
+    it('does not bootstrap until the game is ready', () => {
+        inject(bootstrapper, win as Window, location);
+        jasmine.clock().tick(1000);
+
+        expect(bootstrapper).not.toHaveBeenCalled();
+    });
+
+    it('bootstraps once when the game is ready', () => {
+        win.$ = () => undefined;
+
+        inject(bootstrapper, win as Window, location);
+        jasmine.clock().tick(250);
+
+        expect(bootstrapper).toHaveBeenCalledTimes(1);
+        expect(win.TW_Calc).toBeDefined();
+    });
+
+    it('does not bootstrap again when the script is already injected', () => {
+        win.$ = () => undefined;
+        win.TW_Calc = {}; // a previous injection already set this
+
+        inject(bootstrapper, win as Window, location);
+        jasmine.clock().tick(1000);
+
+        expect(bootstrapper).not.toHaveBeenCalled();
+    });
+});

src/inject.ts

@@ -0,0 +1,42 @@
+import DependencyContainer from 'tsyringe/dist/typings/types/dependency-container';
+import { container } from 'tsyringe';
+
+export function isGameReady(window: Window): boolean {
+    // jquery must be loaded
+    return typeof window['$'] !== 'undefined';
+}
+
+export function isAlreadyInjected(window: Window): boolean {
+    return typeof window['TW_Calc'] !== 'undefined';
+}
+
+// inject script when the game is ready
+export function inject<T>(
+    bootstrapper: (dependencyContainer: DependencyContainer) => T,
+    window: Window,
+    location: Location,
+): ReturnType<typeof setInterval> {
+    const injectInterval = setInterval(() => {
+        if (!isGameReady(window)) {
+            return;
+        }
+        // clear the injector interval
+        clearInterval(injectInterval);
+        // the script may be injected more than once on the page (e.g. re-injection or an
+        // iframe); only bootstrap once, otherwise TheWestApi.register throws "already registered"
+        if (isAlreadyInjected(window)) {
+            return;
+        }
+        // inject the script
+        window['TW_Calc'] = injectScript<T>(bootstrapper, location);
+    }, 250);
+    return injectInterval;
+}
+
+export function injectScript<T>(bootstrapper: (dependencyContainer: DependencyContainer) => T, location: Location): T {
+    const { href } = location;
+    if ((href.indexOf('.the-west.') != -1 || href.indexOf('.tw.innogames.') != -1) && href.indexOf('game.php') != -1) {
+        return bootstrapper(container);
+    }
+    throw new Error('TW-Calc must be loaded in the game!');
+}