jQuery is tailor-made to respond to events in an HTML page.
What are Events?
All the different visitor's actions that a web page can respond to are called events.
An event represents the precise moment when something happens.
Examples:
- moving a mouse over an element
- selecting a radio button
- clicking on an element
The term
"fires" is often used with events. Example:
"The keypress event fires the moment you press a key".
Here are some common DOM events:
| Mouse Events |
Keyboard Events |
Form Events |
Document/Window Events |
| click |
keypress |
submit |
load |
| dblclick |
keydown |
change |
resize |
| mouseenter |
keyup |
focus |
scroll |
| mouseleave |
|
blur |
unload |
jQuery Syntax For Event Methods
In jQuery, most DOM events have an equivalent jQuery method.
To assign a click event to all paragraphs on a page, you can do this:
The next step is to define what should happen when the event fires. You must
pass a function to the event:
$("p").click(function(){
// action goes here!!
});
Commonly Used jQuery Event Methods
$(document).ready()
The $(document).ready() method allows us to execute a function when the
document is fully loaded. This event is already explained in the
jQuery Syntax chapter.
click()
The click() method attaches an event handler function to an HTML element.
The
function is executed when the user clicks on the HTML element.
The following example says: When a click event fires on a <p> element; hide
the current <p> element:
dblclick()
The dblclick() method attaches an event handler function to an HTML element.
The function is executed when the user double-clicks on the HTML element:
mouseenter()
The mouseenter() method attaches an event handler function to an HTML
element.
The function is executed when the mouse pointer enters the HTML element:
Example
$("#p1").mouseenter(function(){
alert("You entered p1!");
});
Try it yourself »
mouseleave()
The mouseleave() method attaches an event handler function to an HTML
element.
The function is executed when the mouse pointer leaves the HTML element:
Example
$("#p1").mouseleave(function(){
alert("Bye! You now leave p1!");
});
Try it yourself »
mousedown()
The mousedown() method attaches an event handler function to an HTML
element.
The function is executed, when the left mouse button is pressed down, while the
mouse is over the HTML element:
Example
$("#p1").mousedown(function(){
alert("Mouse down over p1!");
});
Try it yourself »
mouseup()
The mouseup() method attaches an event handler function to an HTML
element.
The function is executed, when the left mouse button is released, while the
mouse is over the HTML element:
Example
$("#p1").mouseup(function(){
alert("Mouse up over p1!");
});
Try it yourself »
hover()
The hover() method takes two functions and is a combination of the mouseenter() and mouseleave()
methods.
The first
function is executed when the mouse enters the HTML element, and the second
function is
executed when the mouse leaves the HTML element:
Example
$("#p1").hover(function(){
alert("You entered p1!");
},
function(){
alert("Bye! You now leave p1!");
});
Try it yourself »
focus()
The focus() method attaches an event handler function to an HTML form field.
The function is executed when the form field gets focus:
Example
$("input").focus(function(){
$(this).css("background-color","#cccccc");
});
Try it yourself »
blur()
The blur() method attaches an event handler function to an HTML form field.
The function
is executed when the form field loses focus:
Example
$("input").blur(function(){
$(this).css("background-color","#ffffff");
});
Try it yourself »
jQuery Event Methods
For a full jQuery event reference, please go to our
jQuery Events Reference.
