JavaScript/Notes/IBD
Interface Based Design
A formal contract is designed for the interfaces so that the client can choose which interface to use for a given task.
Using a common interface, different Event adapters can be designed to handle different types of event registration:
- Event handler properties
- DOM event registration mechanisms
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>