JavaScript/Notes/CustomEvents

What are they?

An event is a function call that signifies something happened.

Data Received

Example: HSVPicker.

<source lang="javascript"> var transport = new AjaxTransport(url); transport.onsuccess = transportSuccessHandler;

function transportSuccessHandler(ev) {

 var data = ev.data;
 updateTable(data);

} </source>

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>