Event Handling in jQuery

jQuery Events Handling

We have the ability to create dynamic web pages by using events. Events are actions that can be detected by your web application. Following are the examples events : A mouse click A Web page loading Taking mouse over an element Submitting an HTML form A keystroke on your keyboard When these events are triggered you can then use a custom function to do pretty much whatever you want with the event. These custom functions call Event Handlers.

Binding Event Handlers

Using the jQuery Event Model, we can establish event handlers on DOM elements with the bind() method as follows: $(‘div’).bind(‘click’,function(event) { alert(‘Hi there!’); }); This code will cause the division element to respond to the click event; when a user clicks inside this division thereafter, the alert will be shown. The full syntax of the bind() command is as follows: selector.bind(evenType[, evenData], handler) Following is the description of the parameters: EvenType A string containing a JavaScript event type, such as click or submit. Refer to the next section for a complete list of event types. EventData This is optional parameter is a map of data that will be passed to the event handler. Handler A function to execute each time the event is triggered.  

Removing Event Handlers

Typically, once an event handler is established, it remains in effect for the remainder of the life of the page. There may be a need when you would like to remove event handler. jQuery provides the unbind() command to remove an existing event handler. The syntax of unbind() is as follows : selector.unbind(eventType, handler) or selector.unbind(eventType)   Following is the description of the parameters eventType: 

• A string containing a JavaScript listener that.s to be removed.

Event Types

The following are cross platform and recommended event types which you can bind using jQuery

    The Event Object The callback function takes a single parameter, when the handler is called the JavaScript event object will be passed through it. The event object is often unnecessary and the parameter is omitted, as sufficient context is usually available when the handler is bound to know exactly what needs to be done when the handler is triggered. However there are certail attributes which you would need to be accessed.   The Event Attributes The following event properties/attributes are available and safe to access in a platform independent manner.

  Event Helper Methods jQuery also provides a set of event helper functions which can be used either to trigger an event to bind any event types mentioned above.   Trigger Methods Following is an example which would triggers the blur event on all paragraphs: $(“p”).blur();  

Binding Methods in jQuery

Following is an example which would bind a click event on all the <div>: $(“div”).click(function()) { // do something here {); Here is a complete list of all the support methods provided by jQuery