JavaScript/Notes/CustomEvents

What are they?

An event is a function call that signifies something happened.

Custom calls notify subscribers. The function is either defined by the "class" (default) or shadowed on the instance, by the client of the API.

Objects Talking

• Class - defines methods and default handlers
• Instance - shadows class
• Instance usage (from other objects)

Why?

Centralized dispatch. Method called from many places and when it is done, shared notifications fire.

<source lang="javascript"> var tableSort = new Factory(function() {

 function _getSortFunction(sortType) {
   if(sortType == "number") {
    return function() { };
   }
 }

 function _isSortedBy(tableSort, sortType) {

 }

 var configData = {};

 function TableSort(id, config) {
   this.id = id;
   configData[id] = Object.create(config);
 }

 TableSort.prototype.sortBy = function(sortType) {
   var config = configData[this.id];

   if(config.currentSort != sortType) {
     config.sortFunction(this);
     this.onsort(sortType);
   }
 };

 return TableSort;

});

function Factory(getConstructor){

 var i = 0, ctor;
 this.getById = getById;

 function getById(id, config) {
   var instances = this.instances;
   if(!instances) { // First time.
     instances = this.instances = {};
     // Get the constructor.
     ctor = getConstructor(this);
   }
   return instances[id] || (instances[id] = new ctor(id, config));
 }

} </source>