Simplifies the interaction
between HTML document and
JS
Why jQuery?
Open source
Free
Small 18kb
compressed and
114kb uncompressed
Popular
Useful community
support
Chaining
Allows jQuery methods to
be chained
Endless chain on
currently selected jQuery
function
Cuts down on processing
by selecting a set of DOM
elements only once
Wrapper set
Set of elements
wrapped with
jQuery functionality
Can contain
several DOM
elements
Sometimes
contains no
DOM elements
jQuery
methods/properties
will fail silently
Organisation of jQuery API
Organised into logical categories
Makes it easier to narrow down
functionality that's needed
Including jQuery libs in
an HTML page
Use the Google hosted CDN
Download your
own version
Executing jQuery After
the DOM bt b4
complete page load
jQuery ready()
method is typically
bound to the DOM
ready() method
passed a single
param func tht
contains JS code 2
b executed when
DOM ready
Selecting DOM elements
jQuery provides 2
options 2 select
elements from DOM
Using CSS
selectors &
custom
selectors
By passing a str containing
a selector expression 2
jQuery will go through the
DOM & locate the nodes
defined by the expression
Pass the jQuery
function 2 an actual
JS reference 2 DOM
elements (less
Common)
Selecting DOM
elements within
specified context
jQuery function when
passed a CSS
expression will also
accept a 2nd param
that tells the jQuery
function 2 which
context it should
search for the DOM
element
The second param
can b a DOM ref,
jQuery wrapper, or
document
Methods
addClass()
Updates the
class attr val with
a new class/val
hasCLass()
Checks the
value of the
class attr for a
specific class
removeClass()
Removes a
unique class
from the class
attr while
keeping vals
already set
toggleClass()
Adds a specified
class if not present
& removes class if
present