added local events library

js/events.js

@@ -0,0 +1,57 @@
+var EventEmitter = function () {
+  this._events = {};
+};
+
+EventEmitter.prototype.on = function (e, f) {
+  console.log('on', e, f)
+  if (e in this._events) {
+    if (this._events[e].indexOf(f) < 0) {
+      this._events[e].push(f);
+    }
+  } else {
+    this._events[e] = [f];
+  }
+  return this;
+};
+
+EventEmitter.prototype.off = function (e, f) {
+  if (f) {
+    function eq(x) { return function (y) { return x === y; } }
+    this._events[e] = this.listeners(e).filter(eq(f));
+  } else {
+    delete this._events[e];
+  }
+};
+
+EventEmitter.prototype.removeListener = function (e, f) {
+  this.off(e, f);
+};
+
+EventEmitter.prototype.removeAllListeners = function (e) {
+  this.off(e);
+};
+
+EventEmitter.prototype.emit = function (e) {
+  var args = Array.prototype.slice.call(arguments, 1),
+      fs = this.listeners(e);
+      console.log('emit', e, args)
+  
+  for (var i = 0; i < fs.length; i++) {
+    fs[i].apply(e, args);
+  }
+};
+
+EventEmitter.prototype.listeners = function (e) {
+  return this._events[e] || [];
+};
+
+EventEmitter.prototype.once = function (e, f) {
+  var that = this;
+  this.on(e, function g() {
+    f.apply(es, arguments);
+    that.off(e, g);
+  });
+  return this;
+};
+
+exports.EventEmitter = EventEmitter;