Add event adapter example

tshemsedinov · tshemsedinov · commit 85a4d1a942d5 · 2018-11-04T19:03:47.000+02:00
diff --git a/JavaScript/7-events.js b/JavaScript/7-events.js
@@ -0,0 +1,35 @@
+'use strict';
+
+const { EventEmitter } = require('events');
+
+class AdaptiveEmitter extends EventEmitter {
+  constructor() {
+    super();
+    this.transformations = {};
+  }
+  transform(from, to, fn) {
+    this.transformations[from] = { to, fn };
+  }
+  emit(name, ...args) {
+    const transform = this.transformations[name];
+    if (transform) {
+      super.emit(transform.to, ...transform.fn(...args));
+    }
+    super.emit(name, ...args);
+  }
+}
+
+// Usage
+
+const ae = new AdaptiveEmitter();
+ae.transform('timer', 'timeout', date => [date.toLocaleString()]);
+
+ae.on('timeout', date => {
+  console.dir({ date });
+});
+
+setTimeout(() => {
+  const date = new Date();
+  console.log('new Date():', date);
+  ae.emit('timer', date);
+}, 1000);
