Initial reliable release of consent engine

core/events.js

@@ -0,0 +1,104 @@
+/**
+ * Cookie Consent Core
+ * events.js
+ *
+ * Tiny dependency-free event bus.
+ */
+
+export function createEventBus() {
+    const listeners = new Map();
+
+    function on(eventName, callback) {
+        if (typeof eventName !== "string" || !eventName.trim()) {
+            throw new TypeError("eventName must be a non-empty string.");
+        }
+
+        if (typeof callback !== "function") {
+            throw new TypeError("callback must be a function.");
+        }
+
+        if (!listeners.has(eventName)) {
+            listeners.set(eventName, new Set());
+        }
+
+        listeners.get(eventName).add(callback);
+        return () => off(eventName, callback);
+    }
+
+    function once(eventName, callback) {
+        const unsubscribe = on(eventName, (payload) => {
+            unsubscribe();
+            callback(payload);
+        });
+
+        return unsubscribe;
+    }
+
+    function off(eventName, callback) {
+        const callbacks = listeners.get(eventName);
+
+        if (!callbacks) {
+            return false;
+        }
+
+        const removed = callbacks.delete(callback);
+
+        if (callbacks.size === 0) {
+            listeners.delete(eventName);
+        }
+
+        return removed;
+    }
+
+    function emit(eventName, payload) {
+        const callbacks = listeners.get(eventName);
+
+        if (!callbacks) {
+            return;
+        }
+
+        [...callbacks].forEach((callback) => {
+            try {
+                callback(payload);
+            } catch (error) {
+                queueMicrotask(() => {
+                    throw error;
+                });
+            }
+        });
+    }
+
+    function clear(eventName) {
+        if (typeof eventName === "string") {
+            listeners.delete(eventName);
+            return;
+        }
+
+        listeners.clear();
+    }
+
+    function listenerCount(eventName) {
+        return listeners.get(eventName)?.size || 0;
+    }
+
+    return Object.freeze({
+        on,
+        once,
+        off,
+        emit,
+        clear,
+        listenerCount
+    });
+}
+
+export const EVENT_NAMES = Object.freeze([
+    "initialized",
+    "consent:loaded",
+    "consent:accepted",
+    "consent:rejected",
+    "consent:changed",
+    "consent:revoked",
+    "consent:expired",
+    "consent:reset",
+    "storage:error"
+]);