Added an Event dispatcher called EventCaller.js

app/js/EventCaller.js

@@ -0,0 +1,118 @@
+
+
+export class EventCaller{
+  constructor(){
+    this.__listeners = {};
+  }
+
+  get totalListeners(){
+    var count = 0;
+    for (key in Object.keys(this.__listeners)){
+      count += this.__listeners[key].length
+    }
+    return count;
+  }
+
+  is_listening(eventName, callback, owner=null){
+    if (typeof(eventName) !== 'string')
+      throw new TypeError("Expected eventName to be string.");
+    if (eventName.length <= 0)
+      throw new ValueError("Argument eventName cannot be a zero-length string.");
+
+    if (this.__listeners.hasOwnProperty(eventName)){
+      if (typeof(callback) !== 'function')
+        throw new TypeError("Expected callback argument to be a function or class method.");
+      for (var i=0; i < this.__listeners[eventName].length; i++){
+        if (this.__listeners[eventName][i][0] === callback && 
+          this.__listeners[eventName][i][1] === owner){
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  listen(eventName, callback, owner=null, once=false){
+    try{
+      if (!this.is_listening(eventName, callback, owner)){
+        if (!this.__listeners.hasOwnProperty(eventName)){
+          this.__listeners[eventName] = [];
+        }
+        this.__listeners[eventName].push([callback, owner, once]);
+      }
+    } catch (e) {
+      throw e;
+    }
+    return this;
+  }
+
+  unlisten(eventName, callback, owner=null){
+    if (typeof(eventName) !== 'string')
+      throw new TypeError("Expected eventName to be string.");
+    if (eventName.length <= 0)
+      throw new ValueError("Argument eventName cannot be a zero-length string.");
+
+    if (this.__listeners.hasOwnProperty(eventName)){
+      if (typeof(callback) !== 'function')
+        throw new TypeError("Expected callback argument to be a function or class method.");
+      for (var i=0; i < this.__listeners[eventName].length; i++){
+        if (this.__listeners[eventName][i][0] === callback && 
+          this.__listeners[eventName][i][1] === owner){
+          this.__listeners[eventName].splice(i, 1);
+          if (this.__listeners[eventName].length <= 0)
+            delete this.__listeners[eventName];
+          break;
+        }
+      }
+    }
+    return this;
+  }
+
+  unlisten_event(eventName){
+    if (typeof(eventName) !== 'string')
+      throw new TypeError("Expected eventName to be string.");
+    if (eventName.length <= 0)
+      throw new ValueError("Argument eventName cannot be a zero-length string.");
+    if (this.__listener.hasOwnProperty(eventName))
+      delete this.__listener[eventName];
+    return this;
+  }
+
+  unlisten_all(){
+    // NOTE: Perhaps it's better to loop through and delete each property? This should do for now though.
+    this.__listeners = {};
+  }
+
+  emit(eventName, args=null){
+    if (typeof(eventName) !== 'string')
+      throw new TypeError("Expected eventName to be string.");
+    if (eventName.length <= 0)
+      throw new ValueError("Argument eventName cannot be a zero-length string.");
+
+    var once = [];
+    if (this.__listeners.hasOwnProperty(eventName)){
+      for (var i=0; i < this.__listeners[eventName].length; i++){
+        var cb = this.__listeners[eventName][i][0];
+        var own = this.__listeners[eventName][i][1];
+        if (this.__listeners[eventName][i][2] === true)
+          once.push([cb, own]);
+        cb.apply(own, args);
+      }
+
+      if (once.length > 0){
+        for (var i=0; i < once.length; i++){
+          this.unlisten(eventName, once[i][0], once[i][1]);
+        }
+      }
+    }
+
+    return this;
+  }
+}
+
+
+
+
+
+
+