4. Remember
Everything is an Object
Every Object can have instance methods
All objects have prototype
Functions are first-class Objects
JavaScript is multi-paradigm language
Imperative style of C
Object oriented style of Java
Functional style of Lisp
8. Prototype
It is about the abstract not the concrete
Many toolkits is built over it like script.aculo.us
9. $ Function
$() document.getElementById()
$(‘menu’) returns element with id=menu
$(element) if element is a node, it is returned back
$(‘menu’,’menuitem1’,’menuitem2’) return an array of 3
nodes id=menu and menuitem1 and menuitem2
$ extends node returned with useful prototype node
methods
10. $$ Function
$$(), selects node using CSS selectors, support CSS3 selectors
$$(‘li’) select all li elements
$$(‘li.current’) select all li elements of class=current
$$(‘#menu a’) select element all a elements inside of
element with id=menu
$$ extends nodes returned with useful prototype node
methods
11. Enumerable Object
A mixin that provides methods useful for collections
Use in the following classes
Array
Hash
DOM- related objects
Instance Methods:
all; any; collect; detect; each; eachSlice; entries; every; filter;
find; find;All; grep; include; inGroupsOf; inject; inspect; invoke;
map; max; member; min; partition; pluck; reject; select; size;
some; sortBy; toArray; zip
12. each
elem.each(Visitor object)
Implements visitor on each element
Example:
[1,3,4,7,89,6,3,4,5].each(function(elem)
{
alert(elem);
});
13. each
Implement continue using return
Example:
[1,3,4,7,89,6,3,4,5].each(function(elem)
{
if(elem>10)
return;
alert(elem);
});
14. each
Implement break by throw $break
Example:
[1,3,4,7,89,6,3,4,5].each(function(elem)
{
if(elem>10)
return;
if(elem==4)
throw $break;
alert(elem);
});
15. detect
Takes function that returns true/false
Returns first element that returns true
If no match returns undefined
Examples:
[1,3,4,6,8,0,9].detect(function(elem)
{
return elem==0
}));
See also select, reject, partition
16. map
Applies function on each element, pushes the
return into an array that is eventually returned
Example:
[2, 5, 7, 9,50].map(function(item)
{
return item*item;
});
19. Prototype’s DOM extension
Modifying properties of elements
Style and classes
.addClassName(‘class name’)
.removeClassName(‘class name’)
.hasClassName(‘class name’) returns true/false
.toggleClassName(‘class name’)
.setStyle({ prop:val,prop:val,……… })
.getStyle(‘css property’)
20. Prototype’s DOM extension
Modifying DOM
.update(‘ ’)
Change content of element
.replace(‘ ’)
Remove element and add a new one in its place
.insert(‘ ’), insert({top:’ ’,bottom:’ ‘, after:’
‘, before : ‘ ’ })
.remove()
22. Templates
TheTemplate class uses a basic formatting syntax, similar to
Ruby.
The templates are created from strings that use symbols in
the form (e.g., #{fieldName})
The symbols are replaced by actual values when the
template is applied (evaluated) to an object.
23. Example
var myTemplate =
newTemplate('<p>The TV show #{title} was directed
by #{author}.</p>');
// Create hashes with the required values for placeholders
var record1 = {title: 'Metrix', author:'Arun Pandey'};
var record2 = {title: 'Junoon', author:'Manusha'};
var record3 = {title: 'Red Moon', author:'Paul, John'};
var record4 = {title: 'Henai', author:'Robert'};
24. Example
var records = [record1, record2, record3, record4 ];
// Now apply template to produce desired formatted output
records.each( function(conv)
{
$$('p')[0].insert( {bottom: "<div>Formatted Output : " +
myTemplate.evaluate(conv)+"</div>" });
});
}
27. Prototype Form Methods
disable() Disables the form as whole. Form controls will
be visible but uneditable.
enable() Enables a fully or partially disabled form.
28. Prototype Form Methods
findFirstElement() Finds first non-hidden, non-disabled
form control.
focusFirstElement() Gives keyboard focus to the first
element of the form.
getElements() Returns a collection of all form controls
within a form.
29. Prototype Form Methods
getInputs() Returns a collection of all INPUT elements in a
form. Use optional type and name arguments to restrict the
search on these attributes.
request() A convenience method for serializing and
submitting the form via an Ajax.Request to the URL of the
form's action attribute.The options parameter is passed to
the Ajax.Request instance, allowing to override the HTTP
method and to specify additional parameters.
reset() Resets a form to its default values.
31. Element Dimension
Solve problem of inconsistent browser
measurements
.measure(‘ property‘ )
$(‘mydiv’).measure(‘width’) pixel values
For better performance, when measuring more than
one dimension
.getLayout() Layout object
$(‘mydiv’).getLayout().get(‘width’);
http://prototypejs.org/learn/element-layout
33. Events
A single model for all browsers
Event.observe(element,’event’,function{}())
Event.observe(window,’load’,function(){})
Element.observe
$(‘ ’).observe(‘event’,function(){})
34. Events
Can register events on elements or children of an
element.
The selection of children is done using CSS-selectors
Element.on
$(‘ ’).on(‘event’,function(){})
$(‘ ’).on(‘event’,’css selector for child’,function(){})
$(‘item’).on(‘click’,’li’, function(){
………………
});
35. Event Object
All event handlers are receive an event object
function submitFun(evnt)
{
evnt.element() //returns element object that triggered event
evnt.preventDefault() //stop default behaviour
evnt.isLeftClick() or isRightClick() or isMiddleClick()
evnt.pointerX() or pointerY()
evnt.pointer() object{x: , y: }
}
37. Class
Manages Prototype’s class-based OOP system
Class methods:
create()
Instance Methods:
addMethods()
38. Class.create([superclass][, methods...])
superclass (class): superclass to inherit from.
method (object): an object (mix-in) that will be mixed-in to my
new class. Multiple mixins can be used, later mixins take
precedence.
returns a constructor function that can be called using new
operator. It will invoke the initialize method.
The object mixin must contain ‘initialize’ method to be called
when new is called.
43. Encoding
Number#toJSON, String#toJSON,Array#toJSON, Hash#toJSON, Date#toJSON, and
Object.toJSON.
var data = {name: 'Violet', occupation: 'character', age: 25 };
Object.toJSON(data); //-> '{"name": "Violet", "occupation": "character", "age": 25}’
For custom objects,
Set toJSON method which will be used by Object.toJSON.
var Person = Class.create({
initialize: function(name) {
this.name = name;
},
toJSON: function() {
return ('My name is ' + this.name + ' and I am ' + this.age + ' years old.').toJSON();
}
});
var john = new Person('John', 49);
Object.toJSON(john); //-> '"My name is John and I am 49 years old.”’
44. Parsing
String#evalJSON
var data = '{ "name": "Violet", "occupation": "character"
}'.evalJSON();
data.name; //-> "Violet”
46. Ajax
A wrapper class around the XMLHttpRequest
Uses callbacks to handle different phases of the
asynchronous request.
If requested page is a JavaScript code then it is automatically
evaluated and executed.
47. Ajax.Request
new Ajax.Request(URL, Option)
URL : string representing the url to request
Options hash
method
parameters
contentType
onSuccess
onFailure
For complete details:
http://api.prototypejs.org/ajax/
48. Ajax.Updater
Updates a portion of the DOM with external source
new Ajax.Updater(ID , URL , Options)
ID: the id of the element to be updated
URL: url to fetch
Options: hash same as previous
insertion: Insertion.Top
Insertion.Bottom
Insertion.After
Insertion.Before
49. Ajax.PeriodicalUpdater
Runs Updater in periodical Intervals to repeatedly fetch
content from the server.
new Ajax.PeriodicalUpdater(ID, URL, Options)
Same except Options
frequency : interval in seconds
decay : factor to multiply frequency by everytime the fetched
response is the same as the previously fetched.
stop()
start()
