JavaScript/Notes/IBD: Difference between revisions
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Using a common <b>interface</b>, different Event <b>adapters</b> are designed to handle different types of event registration: | Using a common <b>interface</b>, different Event <b>adapters</b> are designed to handle different types of event registration: | ||
# Event handler properties | # Event handler properties | ||
# | # Event callback registration methods | ||
=== Common Interface === | === Common Interface === | ||
Revision as of 11:17, 1 November 2013
Interface Based Design
Using a common interface, different Event adapters are designed to handle different types of event registration:
- Event handler properties
- Event callback registration methods
Common Interface
Each interface shares the following methods: <source lang="javascript"> get(src, sEvent); // Gets an event publisher. addCallback(src, sEvent, callback); removeCallback(o, type, cb[, useCapture); </source>
The DOM events interface has a parameter the capturing phase of the Event phase in removeCallback.
DOM events interface also has special methods for working with DOM events, such as getTarget. However, this is a design smell. Those methods could be refactored to be hidden, and a custom adapted Event instance could be passed to the handler, much like jQuery's adapted event.
Event Handler Properties
Each event is a property name. The value is a function or null. The pattern works equally well for custom events on user-defined objects and DOM events.
DOM Elements <source lang="javascript"> el["onclick"] = function(ev) {
alert(this);
};</source>
Custom Objects and Events <source lang="javascript"> userPicker.onuserselected= function(ev) {
console.log(ev.user + " chosen.");
}; </source>
Event Listener Interface
<source lang="javascript"> el.addEventListener("click", function(ev) {
alert("clicked");
}, false); </source>
Custom objects <source lang="javascript"> userPicker.addCallback("onuserselected", function(ev) {
console.log(ev.user + " chosen.");
}); </source>