✨ running/stopped event

src/helpers/listener.js

@@ -0,0 +1,69 @@
+export class Subject {
+
+  constructor() {
+    this.__listeners = [];
+  }
+
+  next(val) {
+    for (let listener of this.__listeners) {
+      listener(val);
+    }
+  }
+
+  once() {
+    return new Promise((resolve) => {
+      const done = (val) => {
+        resolve(val);
+        this.off(done);
+      };
+      this.on(done);
+    })
+  }
+
+  on(fn) {
+    this.__listeners.push(fn);
+  }
+
+  off(fn) {
+    this.__listeners = this.__listeners.filter((listener) => listener !== fn);
+  }
+
+  destroy() {
+    this.__listeners = [];
+  }
+}
+
+
+
+export class MultiSubject {
+
+  constructor(types) {
+    this.__subjects = {};
+    for (let type of types) {
+      this.__subjects[type] = new Subject();
+    }
+  }
+
+  next(type, val) {
+    this.__subjects[type].next(val);
+  }
+
+  once(type) {
+    return this.__subjects[type].once();
+  }
+
+  on(type, fn) {
+    return this.__subjects[type].on(fn);
+  }
+
+  off(type, fn) {
+    this.__subjects[type].off(fn);
+  }
+
+  destroy() {
+    for (let type of Object.keys(this.__subjects)) {
+      this.__subjects[type].destroy();
+    }
+  }
+}
+