pixel: improve fetching existing PixelControls

src/lib/MetaPixel.svelte

@@ -1,11 +1,36 @@
+<!-- @component
+MetaPixel integrates the Meta (Facebook) Pixel into your Svelte application,
+allowing you to track page views and custom events while respecting user consent
+for tracking. The component manages the lifecycle of the Meta Pixel script and
+PixelControl interface.
+
+The PixelControl class also allows you to directly manage multiple Pixel
+instances and handle event tracking with optional test event codes without
+using the MetaPixel component.
+-->
+
 <script lang="ts" module>
+	export type PixelControlOptions = {
+		/**
+		 * if provided, events fired will always have this code attached
+		 * to prevent them from polluting real analytics data.
+		 */
+		testEventCode?: string;
+		/** Advanced matching data */
+		advancedMatching?: AdvancedMatching;
+		/** Initialization options */
+		initOptions?: InitOptions;
+	};
+
 	export class PixelControl {
 		private _pixelID: string;
 		private _testEventCode?: string = undefined;
 		private _trackingManager: MaybeGetter<TrackingManager | undefined>;
 
 		private static _baseLoaded: boolean = false;
+		private static _registeredPixels: Record<string, PixelControl> = {};
 
+		/** Indicates whether the Meta Pixel base script has been loaded. */
 		static get baseLoaded(): boolean {
 			return this._baseLoaded;
 		}
@@ -24,11 +49,11 @@
 		private constructor(
 			trackingManager: MaybeGetter<TrackingManager | undefined>,
 			pixelID: string,
-			testEventCode?: string
+			options?: PixelControlOptions
 		) {
 			this._trackingManager = trackingManager;
 			this._pixelID = pixelID;
-			this._testEventCode = testEventCode;
+			this._testEventCode = options?.testEventCode;
 		}
 
 		/** Loads the Meta Pixel base script. */
@@ -60,43 +85,55 @@
 		}
 
 		/**
-		 * Returns a PixelControl instance for the given Meta Pixel ID. If
+		 * Registers a PixelControl instance for the given Meta Pixel ID. If
 		 * the base Meta Pixel script has not been loaded yet, it will be
 		 * loaded automatically. Optionally sets a test event code for the Pixel.
-		 * Does NOT initialize the Pixel; call `fireInit()` on the returned instance
-		 * before tracking events.
+		 * Should only be called once for each Pixel ID, use PixelControl.get()
+		 * to retrieve existing instances.
 		 * @param trackingManager Tracking manager to handle user consent for tracking
 		 * @param pixelID Meta Pixel ID
 		 * @param options Optional settings
 		 * @returns PixelControl instance
 		 */
-		static for(
+		static initialize(
 			trackingManager: MaybeGetter<TrackingManager | undefined>,
 			pixelID: string,
-			options?: {
-				/**
-				 * if provided, events fired will always have this code attached
-				 * to prevent them from polluting real analytics data.
-				 */
-				testEventCode?: string;
-			}
+			options?: PixelControlOptions
 		): PixelControl {
+			// Load the base script if not already loaded
 			PixelControl.load();
-			return new PixelControl(trackingManager, pixelID, options?.testEventCode);
+
+			// Check for existing PixelControl instance
+			if (this._registeredPixels[pixelID]) {
+				log.warn(
+					`PixelControl instance for Meta Pixel ID: ${pixelID} already exists. Returning existing instance.`
+				);
+				return this._registeredPixels[pixelID];
+			}
+
+			// Create and register the PixelControl instance
+			const pixel = new PixelControl(trackingManager, pixelID, options);
+			this._registeredPixels[pixelID] = pixel;
+
+			// Fire initialization
+			window.fbq('init', pixel._pixelID, options?.advancedMatching, options?.initOptions);
+			log.debug(`Meta Pixel [${pixel._pixelID}] initialized.`);
+
+			return pixel;
 		}
 
 		/**
-		 * Initializes this pixel with the Meta Pixel API including any advanced
-		 * matching data and options.
-		 * @param advancedMatching Advanced matching data
-		 * @param initOptions Initialization options
-		 * @returns this PixelControl instance
+		 * Returns an existing PixelControl instance for the given Meta Pixel ID.
+		 * @param pixelID Meta Pixel ID
+		 * @returns PixelControl instance
+		 * @throws Error if no PixelControl instance is found for the given ID.
 		 */
-		fireInit(advancedMatching?: AdvancedMatching, initOptions?: InitOptions): PixelControl {
-			PixelControl.loadGuard();
-			window.fbq('init', this._pixelID, advancedMatching, initOptions);
-			log.debug(`Meta Pixel [${this._pixelID}] initialized.`);
-			return this;
+		static get(pixelID: string): PixelControl {
+			const pixel = this._registeredPixels[pixelID];
+			if (!pixel) {
+				throw new Error(`No PixelControl instance found for Meta Pixel ID: ${pixelID}`);
+			}
+			return pixel;
 		}
 
 		/**
@@ -156,7 +193,7 @@
 </script>
 
 <script lang="ts">
-	import { onMount } from 'svelte';
+	import { createContext, onMount } from 'svelte';
 
 	import type { TrackingManager } from './tracking.svelte.ts';
 	import type {
@@ -173,30 +210,27 @@
 	import log from 'loglevel';
 
 	interface Props {
-		/** Meta Pixel ID */
-		pixelID: string;
-
-		/**
-		 * If a test event code is available, events fired will always have this
-		 * code attached to prevent them from polluting real analytics data.
-		 */
-		testEventCode?: string;
-
-		/**
-		 * Controls whether page views are automatically tracked by this
-		 * component (default: true).
-		 */
-		autoPageView?: boolean;
-
 		/**
 		 * Tracking manager to handle user consent for tracking. If omitted
 		 * tracking is disabled by default until consent is granted via
 		 * PixelControl.grantConsent().
 		 */
 		trackingManager?: TrackingManager;
+
+		/** Meta Pixel ID */
+		pixelID: string;
+
+		/** Meta Pixel Options */
+		pixelOptions?: PixelControlOptions;
+
+		/**
+		 * Controls whether page views are automatically tracked by this
+		 * component (default: true).
+		 */
+		autoPageView?: boolean;
 	}
 
-	let { pixelID, testEventCode, autoPageView = true, trackingManager }: Props = $props();
+	let { pixelID, pixelOptions, autoPageView = true, trackingManager }: Props = $props();
 
 	let pixel = $state<PixelControl | null>(null);
 
@@ -205,7 +239,7 @@
 			throw new Error('MetaPixel component requires a TrackingManager to manage consent.');
 		}
 		PixelControl.load();
-		pixel = PixelControl.for(trackingManager, pixelID, { testEventCode }).fireInit();
+		pixel = PixelControl.initialize(trackingManager, pixelID, pixelOptions);
 
 		trackingManager.runWithConsent(() => {
 			if (autoPageView && pixel) {
@@ -221,4 +255,11 @@
 			}
 		});
 	});
+
+	export const getPixelControl = (): PixelControl => {
+		if (!pixel) {
+			throw new Error('MetaPixel component has not been initialized yet, wait for onMount.');
+		}
+		return pixel;
+	};
 </script>