PrototypeMerge
our complete prototype documenation in one page
Created by: xing, Last modification: 28 Dec 2005 (00:35 UTC) by Stephan Borg
Here you can find all our Prototype Documentation on one massive page.
Prototype is a JavaScript framework that aims to ease development of dynamic web applications. Featuring a unique, easy-to-use toolkit for class-driven development and the nicest Ajax library around, Prototype is quickly becoming the codebase of choice for Web 2.0 developers everywhere.
Please be advised that prototype can adversely effect some existing javascripts and in places it secretly modifies some of JavaScripts default behavior. Before proceeding with prototype it is worth considering James Mc Parlane's Rejection of prototype.
The Documentation is split among the following pages:
Easy AJAX with Prototype [24-ways.org]
Prototype Library Info [blogs.ebusiness-apps.com]
Quick Guide To Prototype [particletree.com]
Debugging AJAX Requests in Prototype [ajaxian.com]
http://www.sergiopereira.com/articles/prototype.js.html
We hope to make this documenation more accessible by using a wiki for easy access and maintenance.
The library comes with many predefined objects and utility functions. The obvious goal of these functions is to save you a lot of repeated typing and idioms.
The $() function is a handy shortcut to the all-too-frequent document.getElementById() function of the DOM. Like the DOM function, this one returns the element that has the id passed as an argument.
Unlike the DOM function, though, this one goes further. You can pass more than one id and $() will return an Array object with all the requested elements. The example below should illustrate this.
Another nice thing about this function is that you can pass either the id string or the element object itself, which makes this function very useful when creating other functions that can also take either form of argument.
The $F() function is a another welcome shortcut. It returns the value of any field input control, like text boxes or drop-down lists. The function can take as argument either the element id or the element object itself.
The Try.these() function makes it easy when you want to, ahem, try different function calls until one of them works. It takes a number of functions as arguments and calls them one by one, in sequence, until one of them works, returning the result of that successful function call.
In the example below, the function xmlNode.text works in some browsers, and xmlNode.textContent works in the other browsers. Using the Try.these() function we can return the one that works.
This collection of classes and functions extends existing Javascript classes and functions. They simplfy such things as manipulating text, adding keyboard commands, adding inheretance, and other random things.
One of the ways the prototype.js library adds functionality is by extending the existing JavaScript classes.
Let's see one of these extensions in action.
Let's see how to use this object to add an event handler to the load event of the window object.
Another way the library helps you is by providing many objects implement both support for object oriented designs and common functionality in general.
This object provides the logic for calling a given function repeatedly, at a given interval.
The Prototype object does not have any important role, other than declaring the version of the library being used.
The Class object is used when declaring the other classes in the library. Using this object when declaring a class causes the to new class to support an initialize() method, which serves as the constructor.
See the sample below.
The following are objects and functions of the Prototype library that simplify the tricky code that is involved in manipulating Dom Elements, such as text, divs, forms, fields, etc.
These functions are great for changing text on a page, monitoring changes made to forms, and adding and removing addition page parts.
Also see the PrototypeUtilityFunctions, some of which are handy to use when manipulating Elements.
This object provides some utility functions for manipulating elements in the DOM.
This object serves as the root for other classes in the library. It does not have any properties or methods. The classes defined in this object are also treated as traditional abstract classes.
This class is used as the base class for the other classes that will provide dynamic content insertion. This class is used like an abstract class.
This object serves as the root for other classes in the library. It does not have any properties or methods. The classes defined in this object are also treated as traditional abstract classes.
Inherits from Abstract.Insertion
Inserts HTML before an element.
The following code
Will change the HTML to
Inherits from Abstract.Insertion
Inserts HTML as the first child under an element. The content will be right after the opening tag of the element.
The following code
Will change the HTML to
Inherits from Abstract.Insertion
Inserts HTML as the last child under an element. The content will be right before the element's closing tag.
The following code
Will change the HTML to
Inherits from Abstract.Insertion
Inserts HTML right after the element's closing tag.
The following code
Will change the HTML to
This object provides a host of functions that help when working with element positioning.
This object provides some utility functions for working with input fields in forms.
This object provides some utility functions for working with data entry forms and their input fields.
This object provides some utility functions for working with form elements, visible or not.
This object provides some utility functions that are used internally in the library to assist extracting the current value of the form elements.
This class is used as the base class for the other classes that will monitor one element until its value (or whatever property the derived class defines) changes. This class is used like an abstract class.
Subclasses can be created to monitor things like the input value of an element, or one of the style properties, or number of rows in a table, or whatever else you may be interested in tracking changes to.
||Method | Kind | Arguments | Description
ctor(element, frequency, callback) | constructor | element: element object or id, frequency: interval in seconds, callback: function to be called when the element changes | Creates an object that will monitor the element.
The Ajax object is a pre-defined object, created by the library to wrap and simplify the tricky code that is involved when writing AJAX functionality. This object serves as the root for many other classes that provide AJAX functionality. This object contains a number of classes that provide encapsulated AJAX logic.
This class is used as the base class for the other classes defined in the Ajax object.
Inherits from Ajax.Base
Encapsulates AJAX operations
An important part of the AJAX operations is the options argument. There's no options class per se. Any object can be passed, as long as it has the expected properties. It is common to create anonymous objects just for the AJAX calls.
Inherits from Ajax.Request
Used when the requested url returns HTML that you want to inject directly in a specific element of your page. You can also use this object when the url returns <script> blocks that will be evaluated upon arrival. Use the evalScripts option to work with scripts.
Inherits from Ajax.Base
This class repeatedly instantiates and uses an Ajax.Updater object to refresh an element on the page, or to perform any of the other tasks the Ajax.Updater can perform. Check the Ajax.Updater reference for more information.
If you are not using any helper library, you are probably writing a whole lot of code to create a XMLHttpRequest object and then track its progress asynchronously, then extract the response and process it. And consider yourself lucky if you do not have to support more than one
type of browser.
To assist with AJAX functionality, the library defines the Ajax.Request class.
Let's say you have an application that can communicate with the server via the url http://yoursever/app/get_sales?empID=1234&year=1998, which returns an XML response like the following.
Talking to the server to retrieve this XML is pretty simple using an Ajax.Request object. The sample below shows how it can be done.
Can you see the second parameter passed to the constructor of the Ajax.Request object? The parameter {method: 'get', parameters: pars, onComplete: showResponse} represents an anonymous object in literal notation. What it means is that we are passing an object that has a property named method that contains the string 'get', another property named parameters that contains the querystring of the HTTP request, and an onComplete property/method containing the function showResponse.
There are a few other properties that you can define and populate in this object, like asynchronous, which can be true or false and determines if the AJAX call to the server will be made asynchronously (the default value is true.)
This parameter defines the options for the AJAX call. In our sample, we are calling the url in the first argument via a HTTP GET command, passing the querystring contained in the variable pars, and the Ajax.Request object will call the showResponse function when it finishes retrieving the response.
As you may know, the XMLHttpRequest reports progress during the HTTP call. This progress can inform four different stages: Loading, Loaded, Interactive, or Complete. You can make the Ajax.Request object call a custom function in any of these stages, the Complete being the most common one. To inform the function to the object, simply provide property/methods named onXXXXX in the request options, just like the onComplete from our example. The function you pass in will be called by the object with one argument, which will be the XMLHttpRequest object itself. You can then use this object to get the returned data and maybe check the status property, which will contain the HTTP result code of the call.
Two other interesting options can be used to process the results. We can specify the onSuccess option as a function to be called when the AJAX call executes without errors and, conversily, the onFailure option can be a function to be called when a server error happens. Just like the onXXXXX option functions, these two will also be called passing the XMLHttpRequest object that carried the AJAX call.
Our sample did not process the XML response in any interesting way. We just dumped the XML in the textarea. A typical usage of the response would probably find the desired information inside the XML and update some page elements, or maybe even some sort of XSLT transformation to produce HTML in the page.
For more complete explanations, see the Ajax.Request reference and the options reference.
If you have a server endpoint that can return information already formatted in HTML, the library makes life even easier for you with the Ajax.Updater class. With it you just inform which element should be filled with the HTML returned from the AJAX call. An example speaks better that I can write.
As you can see, the code is very similar to the previous example, with the exclusion of the onComplete function and the element id being passed in the constructor. Let's change the code a little bit to illustrate how it is possible to handle server errors on the client.
We will add more options to the call, specifying a function to capture error conditions. This is done using the onFailure option. We will also specify that the placeholder only gets populated in case of a successful operation. To achieve this we will change the first parameter from a simple element id to an object with two properties, success (to be used when everything goes OK) and failure (to be used when things go bad.) We will not be using the failure property in our example, just the reportError function in the onFailure option.
If your server logic returns JavaScript code instead of HTML markup, the Ajax.Updater object can evaluate that JavaScript code. To get the object to treat the response as JavaScript, you simply add evalScripts: true; to the list of properties in the last argument of the object constructor.
For more complete explanations, see the Ajax.Updater reference and the options reference.
Complete Protoype Documenation
This is Documentation for the Javascript library Prototype.
Prototype is a JavaScript framework that aims to ease development of dynamic web applications. Featuring a unique, easy-to-use toolkit for class-driven development and the nicest Ajax library around, Prototype is quickly becoming the codebase of choice for Web 2.0 developers everywhere.
Please be advised that prototype can adversely effect some existing javascripts and in places it secretly modifies some of JavaScripts default behavior. Before proceeding with prototype it is worth considering James Mc Parlane's Rejection of prototype.
The Documentation is split among the following pages:
- PrototypeUtilityFunctions
Commonly used javascript functions shortened to save you time. - PrototypeJavascriptExtensions
Extensions of Javascripts existing classes and functions - PrototypeElementFunctions
For basic Dom Element manipulation - PrototypeAjaxObject
Simplified AJAX handling - PrototypeMerge
All Prototype Documentation on Bitweaver.org on one page
Prototype Use In Bitweaver
You can find Bitweaver Packages that use Prototype and instructions for including the Prototype library in your package here: PrototypeUseInBitweaverPrototype Tutorials and Examples
There are some examples in the documentation here on bw.o, but here are some more sample uses of Prototype found around the web:Easy AJAX with Prototype [24-ways.org]
Prototype Library Info [blogs.ebusiness-apps.com]
Quick Guide To Prototype [particletree.com]
Debugging AJAX Requests in Prototype [ajaxian.com]
Credits and About
This documentation is based on the original documentation here:http://www.sergiopereira.com/articles/prototype.js.html
We hope to make this documenation more accessible by using a wiki for easy access and maintenance.
The utility functions
The library comes with many predefined objects and utility functions. The obvious goal of these functions is to save you a lot of repeated typing and idioms.
Using the $() function
The $() function is a handy shortcut to the all-too-frequent document.getElementById() function of the DOM. Like the DOM function, this one returns the element that has the id passed as an argument.
Unlike the DOM function, though, this one goes further. You can pass more than one id and $() will return an Array object with all the requested elements. The example below should illustrate this.
<html>
<head>
<title> Test Page </title>
<script src="prototype-1.3.1.js"></script>
<script>
function test1() {
var d = $('myDiv');
alert(d.innerHTML);
}
function test2() {
var divs = $('myDiv','myOtherDiv');
for(i=0; i<divs.length; i++) {
alert(divs[i].innerHTML);
}
}
</script>
</head>
<body>
<div id="myDiv">
<p>This is a paragraph</p>
</div>
<div id="myOtherDiv">
<p>This is another paragraph</p>
</div>
<input type="button" value=Test1 onclick="test1();"><br>
<input type="button" value=Test2 onclick="test2();"><br>
</body>
</html>
Another nice thing about this function is that you can pass either the id string or the element object itself, which makes this function very useful when creating other functions that can also take either form of argument.
Using the $F() function
The $F() function is a another welcome shortcut. It returns the value of any field input control, like text boxes or drop-down lists. The function can take as argument either the element id or the element object itself.
<script>
function test3() {
alert( $F('userName') );
}
</script>
<input type="text" id="userName" value="Joe Doe"><br>
<input type="button" value=Test3 onclick="test3();"><br>
Using the Try.these() function
The Try.these() function makes it easy when you want to, ahem, try different function calls until one of them works. It takes a number of functions as arguments and calls them one by one, in sequence, until one of them works, returning the result of that successful function call.
In the example below, the function xmlNode.text works in some browsers, and xmlNode.textContent works in the other browsers. Using the Try.these() function we can return the one that works.
<script>
function getXmlNodeValue(xmlNode){
return Try.these(
function() {return xmlNode.text;},
function() {return xmlNode.textContent;}
);
}
</script>
Extensions to various classes
This collection of classes and functions extends existing Javascript classes and functions. They simplfy such things as manipulating text, adding keyboard commands, adding inheretance, and other random things.
Extensions to the JavaScript classes
One of the ways the prototype.js library adds functionality is by extending the existing JavaScript classes.
Extensions for the Object class
| Method | Kind | Arguments | Description |
| extend(destination, source) | static | destination: any object, source: any object | Provides a way to implement inheritance by copying all properties and methods from source to destination. |
| extend(object) | instance | any object | Provides a way to implement inheritance by copying all properties and methods from the given object. |
Extensions for the Number class
| Method | Kind | Arguments | Description |
| toColorPart() | instance | (none) | Returns the hexadecimal representation of the number. Useful when converting the RGB components of a color into its HTML representation. |
Extensions for the Function class
| Method | Kind | Arguments | Description |
| bind(object) | instance | object: the object that owns the method | Returns an instance of the function pre-bound to the function(=method) owner object. The returned function will have the same arguments as the original one. |
| bindAsEventListener(object) | instance | object: the object that owns the method | Returns an instance of the function pre-bound to the function(=method) owner object.The returned function will have the current event object as its argument. |
Let's see one of these extensions in action.
<input type=checkbox id=myChk value=1 /> Test?
<script>
//declaring the class
var CheckboxWatcher = Class.create();
//defining the rest of the class implmentation
CheckboxWatcher.prototype = {
initialize: function(chkBox, message) {
this.chkBox = $(chkBox);
this.message = message;
//assigning our method to the event
this.chkBox.onclick = this.showMessage.bindAsEventListener(this);
},
showMessage: function(evt) {
alert(this.message + ' (' + evt.type + ')');
}
};
var watcher = new CheckboxWatcher('myChk', 'Changed');
</script>
Extensions for the String class
| Method | Kind | Arguments | Description |
| stripTags() | instance | (none) | Returns the string with any HTML or XML tags removed |
| escapeHTML() | instance | (none) | Returns the string with any HTML markup characters properly escaped |
| unescapeHTML() | instance | (none) | The reverse of escapeHTML() |
Extensions for the document DOM object
| Method | Kind | Arguments | Description |
| getElementsByClassName(className) | instance | className: name of a CSS class associated with the elements | Returns all the elements that are associated with the given class name. |
Extensions for the Event object
| Property | Type | Description | |
| KEY_BACKSPACE | Number | 8: Constant. Code for the Backspace key. | |
| KEY_TAB | Number | 9: Constant. Code for the Tab key. | |
| KEY_RETURN | Number | 13: Constant. Code for the Return key. | |
| KEY_ESC | Number | 27: Constant. Code for the Esc key. | |
| KEY_LEFT | Number | 37: Constant. Code for the Left arrow key. | |
| KEY_UP | Number | 38: Constant. Code for the Up arrow key. | |
| KEY_RIGHT | Number | 39: Constant. Code for the Right arrow key. | |
| KEY_DOWN | Number | 40: Constant. Code for the Down arrow key. | |
| KEY_DELETE | Number | 46: Constant. Code for the Delete key. | |
| observers: | Array | List of cached observers. Part of the internal implementation details of the object. | |
| Method | Kind | Arguments | Description |
| element(event) | static | event: an Event object | Returns element that originated the event. |
| isLeftClick(event) | static | event: an Event object | Returns true if the left mouse button was clicked. |
| pointerX(event) | static | event: an Event object | Returns the x coordinate of the mouse pointer on the page. |
| pointerY(event) | static | event: an Event object | Returns the y coordinate of the mouse pointer on the page. |
| stop(event) | static | event: an Event object | Use this function to abort the default behavior of an event and to suspend its propagation. |
| findElement(event, tagName) | static | event: an Event object, tagName: name of the desired tag. | Traverses the DOM tree upwards, searching for the first element with the given tag name, starting from the element that originated the event. |
| observe(element, name, observer, useCapture) | static | element: object or id, name: event name (like 'click', 'load', etc), observer: function to handle the event, useCapture: if true, handles the event in the capture phase and if false in the bubbling phase. | Adds an event handler function to an event. |
| stopObserving(element, name, observer, useCapture) | static | element: object or id, name: event name (like 'click'), observer: function that is handling the event, useCapture: if true handles the event in the capture phase and if false in the bubbling phase. | Removes an event handler from the event. |
| _observeAndCache(element, name, observer, useCapture) | static | Private method, do not worry about it. | |
| unloadCache() | static | (none) | Private method, do not worry about it. Clears all cached observers from memory. |
Let's see how to use this object to add an event handler to the load event of the window object.
<script>
Event.observe(window, 'load', showMessage, false);
function showMessage() {
alert('Page loaded.');
}
</script>
New objects and classes defined by prototype.js
Another way the library helps you is by providing many objects implement both support for object oriented designs and common functionality in general.
The PeriodicalExecuter object
This object provides the logic for calling a given function repeatedly, at a given interval.
| Method | Kind | Arguments | Description |
| ctor(callback, interval) | constructor | callback: a parameterless function, interval: number of seconds | Creates one instance of this object that will call the function repeatedly. |
| Property | Type | Description | |
| callback | Function() | The function to be called. No parameters will be passed to it. | |
| frequency | Number | This is actually the interval in seconds | |
| currentlyExecuting | Boolean | Indicates if the function call is in progress | |
The Prototype object
The Prototype object does not have any important role, other than declaring the version of the library being used.
| Property | Type | Description | |
| Version | String | The version of the library | |
| emptyFunction | Function() | An empty function object | |
The Class object
The Class object is used when declaring the other classes in the library. Using this object when declaring a class causes the to new class to support an initialize() method, which serves as the constructor.
See the sample below.
<script>
//declaring the class
var MySampleClass = Class.create();
//defining the rest of the class implmentation
MySampleClass.prototype = {
initialize: function(message) {
this.message = message;
},
showMessage: function(ajaxResponse) {
alert(this.message);
}
};
//now, let's instantiate and use one object
var myTalker = new MySampleClass('hi there.');
myTalker.showMessage(); //displays alert
</script>
| Method | Kind | Arguments | Description |
| create(*) | instance | (any) | Defines a constructor for a new class |
The following are objects and functions of the Prototype library that simplify the tricky code that is involved in manipulating Dom Elements, such as text, divs, forms, fields, etc.
These functions are great for changing text on a page, monitoring changes made to forms, and adding and removing addition page parts.
Also see the PrototypeUtilityFunctions, some of which are handy to use when manipulating Elements.
HTML and Basic Element Manipulation
The Element object
This object provides some utility functions for manipulating elements in the DOM.
| Method | Kind | Arguments | Description |
| toggle(elem1 [, elem2 [, elem3 ...]]) | instance | elemN: element object or id | Toggles the visibility of each passed element. |
| hide(elem1 [, elem2 [, elem3 ...]]) | instance | elemN: element object or id | Hides each element by setting its style.display to 'none'. |
| show(elem1 [, elem2 [, elem3 ...]]) | instance | elemN: element object or id | Shows each element by resetting its style.display to ''. |
| remove(element) | instance | element: element object or id | Removes the element from the document. |
| getHeight(element) | instance | element: element object or id | Returns the offsetHeight of the element |
| addClassName(element, className) | instance | element: element object or id, className: name of a CSS class | Adds the given class name to the element's class names. |
| hasClassName(element, className) | instance | element: element object or id, className: name of a CSS class | Returns true if the element has the given class name as one of its class names. |
| removeClassName(element, className) | instance | element: element object or id, className: name of a CSS class | Removes the given class name from the element's class names. |
| cleanWhitespace(element) | instance | element: element object or id | Removes any white space text node children of the element |
The Abstract object
This object serves as the root for other classes in the library. It does not have any properties or methods. The classes defined in this object are also treated as traditional abstract classes.
The Abstract.Insertion class
This class is used as the base class for the other classes that will provide dynamic content insertion. This class is used like an abstract class.
| Method | Kind | Arguments | Description |
| ctor(element, content) | constructor | element: element object or id, content: HTML to be inserted | Creates an object that will help with dynamic content insertion. |
| Property | Type | Kind | Description |
| adjacency | String | static, parameter | Parameter that specifies where the content will be placed relative to the given element. The possible values are: 'beforeBegin', 'afterBegin', 'beforeEnd', and 'afterEnd'. |
| element | Object | instance | The element object that the insertion will be made relative to. |
| content | String | instance | The HTML that will be inserted. |
The Insertion object
This object serves as the root for other classes in the library. It does not have any properties or methods. The classes defined in this object are also treated as traditional abstract classes.
The Insertion.Before class
Inherits from Abstract.Insertion
Inserts HTML before an element.
| Method | Kind | Arguments | Description |
| ctor(element, content) | constructor | element: element object or id, content: HTML to be inserted | Inherited from Abstract.Insertion. Creates an object that will help with dynamic content insertion. |
The following code
<br>Hello, <span id="person" style="color:red;">Wiggum. How is it going?</span>
<script> new Insertion.Before('person', 'Chief '); </script>
Will change the HTML to
<br>Hello, Chief <span id="person" style="color:red;">Wiggum. How is it going?</span>
The Insertion.Top class
Inherits from Abstract.Insertion
Inserts HTML as the first child under an element. The content will be right after the opening tag of the element.
| Method | Kind | Arguments | Description |
| ctor(element, content) | constructor | element: element object or id, content: HTML to be inserted | Inherited from Abstract.Insertion. Creates an object that will help with dynamic content insertion. |
The following code
<br>Hello, <span id="person" style="color:red;">Wiggum. How is it going?</span>
<script> new Insertion.Before('person', 'Mr. '); </script>
Will change the HTML to
<br>Hello, <span id="person" style="color:red;">Mr. Wiggum. How is it going?</span>
The Insertion.Bottom class
Inherits from Abstract.Insertion
Inserts HTML as the last child under an element. The content will be right before the element's closing tag.
| Method | Kind | Arguments | Description |
| ctor(element, content) | constructor | element: element object or id, content: HTML to be inserted | Inherited from Abstract.Insertion. Creates an object that will help with dynamic content insertion. |
The following code
<br>Hello, <span id="person" style="color:red;">Wiggum. How is it going?</span>
<script> new Insertion.Before('person', ' What's up?'); </script>
Will change the HTML to
<br>Hello, <span id="person" style="color:red;">Wiggum. How is it going? What's up?</span>
The Insertion.After class
Inherits from Abstract.Insertion
Inserts HTML right after the element's closing tag.
| Method | Kind | Arguments | Description |
| ctor(element, content) | constructor | element: element object or id, content: HTML to be inserted | Inherited from Abstract.Insertion. Creates an object that will help with dynamic content insertion. |
The following code
<br>Hello, <span id="person" style="color:red;">Wiggum. How is it going?</span>
<script> new Insertion.Before('person', ' Are you there?'); </script>
Will change the HTML to
<br>Hello, <span id="person" style="color:red;">Wiggum. How is it going?</span> Are you there?
The Position object (preliminary documentation)
This object provides a host of functions that help when working with element positioning.
| Method | Kind | Arguments | Description |
| prepare() | instance | (none) | Adjusts the deltaX and deltaY properties to accommodate changes in the scroll position. Remember to call this method before any calls to withinIncludingScrolloffset after the page scrolls. |
| realOffset(element) | instance | element: object | Returns an Array with the correct scroll offsets of the element, including any scroll offsets that affect the element. The resulting array is similar to total_scroll_left, total_scroll_top |
| cumulativeOffset(element) | instance | element: object | Returns an Array with the correct positioning offsets of the element, including any offsets that are imposed by positioned parent elements. The resulting array is similar to total_offset_left, total_offset_top |
| within(element, x, y) | instance | element: object, x and y: coordinates of a point | Tests if the given point coordinates are inside the bounding rectangle of the given element |
| withinIncludingScrolloffsets(element, x, y) | instance | element: object, x and y: coordinates of a point | |
| overlap(mode, element) | instance | mode: 'vertical' or 'horizontal', element: object | within() needs to be called right before calling this method. This method will return a decimal number between 0.0 and 1.0 representing the fraction of the coordinate that overlaps on the element. As an example, if the element is a square DIV with a 100px side and positioned at (300, 300), then within(divSquare, 330, 330); overlap('vertical', divSquare); should return 0.10, meaning that the point is at the 10% (30px) mark from the top border of the DIV. |
| clone(source, target) | instance | source: element object or id, target: element object or id | Resizes and repositions the target element identically to the source element. |
Form and Field Element Manipulation
The Field object
This object provides some utility functions for working with input fields in forms.
| Method | Kind | Arguments | Description |
| clear(field1 [, field2 [, field3 ...]]) | instance | fieldN: field element object or id | Clears the value of each passed form field element. |
| present(field1 [, field2 [, field3 ...]]) | instance | fieldN: field element object or id | Returns true only if all forms fields contain non-empty values. |
| focus(field) | instance | field: field element object or id | Moves the input focus to the given form field. |
| select(field) | instance | field: field element object or id | Selects the value in fields that support text selection |
| activate(field) | instance | field: field element object or id | Move the focus and selects the value in fields that support text selection |
The Form object
This object provides some utility functions for working with data entry forms and their input fields.
| Method | Kind | Arguments | Description |
| serialize(form) | instance | form: form element object or id | Returns a url-formatted list of field names and their values, like 'field1=value1&field2=value2&field3=value3' |
| getElements(form) | instance | form: form element object or id | Returns an Array containing all the input fields in the form. |
| getInputs(form [, typeName , name]) | instance | form: form element object or id, typeName: the type of the input element, name: the name of the input element. | Returns an Array containing all the <input> elements in the form. Optionally, the list can be filtered by the type or name attributes of the elements. |
| disable(form) | instance | form: form element object or id | Disables all the input fields in the form. |
| enable(form) | instance | form: form element object or id | Enables all the input fields in the form. |
| focusFirstElement(form) | instance | form: form element object or id | Activates the first visible, enabled input field in the form. |
| reset(form) | instance | form: form element object or id | Resets the form. The same as calling the reset() method of the form object. |
The Form.Element object
This object provides some utility functions for working with form elements, visible or not.
| Method | Kind | Arguments | Description |
| serialize(element) | instance | element: element object or id | Returns the element's name=value pair, like 'elementName=elementValue' |
| getValue(element) | instance | element: element object or id | Returns the value of the element. |
The Form.Element.Serializers object
This object provides some utility functions that are used internally in the library to assist extracting the current value of the form elements.
| Method | Kind | Arguments | Description |
| inputSelector(element) | instance | element: object or id of a form element that has the checked property, like a radio button or checkbox. | Returns an Array with the element's name and value, like elementName', 'elementValue>'elementName', 'elementValue' |
| textarea(element) | instance | element: object or id of a form element that has the value property, like a textbox, button or password field. | Returns an Array with the element's name and value, like elementName', 'elementValue>'elementName', 'elementValue' |
| select(element) | instance | element: object or id of a <select> element | Returns an Array with the element's name and all selected options' values or texts, like elementName', 'selOpt1 selOpt4 selOpt9>'elementName', 'selOpt1 selOpt4 selOpt9' |
Element Listening
The Abstract.TimedObserver class
This class is used as the base class for the other classes that will monitor one element until its value (or whatever property the derived class defines) changes. This class is used like an abstract class.
Subclasses can be created to monitor things like the input value of an element, or one of the style properties, or number of rows in a table, or whatever else you may be interested in tracking changes to.
||Method | Kind | Arguments | Description
ctor(element, frequency, callback) | constructor | element: element object or id, frequency: interval in seconds, callback: function to be called when the element changes | Creates an object that will monitor the element.
The Ajax object
The Ajax object is a pre-defined object, created by the library to wrap and simplify the tricky code that is involved when writing AJAX functionality. This object serves as the root for many other classes that provide AJAX functionality. This object contains a number of classes that provide encapsulated AJAX logic.
| Method | Kind | Arguments | Description |
| getTransport() | instance | (none) | Returns a new XMLHttpRequest object |
The Ajax.Base class
This class is used as the base class for the other classes defined in the Ajax object.
| Method | Kind | Arguments | Description |
| setOptions(options) | instance | options: AJAX options | Sets the desired options for the AJAX operation |
| responseIsSuccess() | instance | (none) | Returns true if the AJAX operation succeeded, false otherwise |
| responseIsFailure() | instance | (none) | The opposite of responseIsSuccess(). |
The Ajax.Request class
Inherits from Ajax.Base
Encapsulates AJAX operations
| Property | Type | Kind | Description |
| Events | Array | static | List of possible events/statuses reported during an AJAX operation. The list contains: 'Uninitialized', 'Loading', 'Loaded', 'Interactive', and 'Complete.' |
| transport | XMLHttpRequest | instance | The XMLHttpRequest object that carries the AJAX operation |
| Method | Kind | Arguments | Description |
| ctor(url, options) | constructor | url: the url to be fetched, options: AJAX options | Creates one instance of this object that will call the given url using the given options. Important: It is worth noting that the chosen url is subject to the borwser's security settings. In many cases the browser will not fetch the url if it is not from the same host (domain) as the current page. You should ideally use only local urls to avoid having to configure or restrict the user's browser. (Thanks Clay). |
| request(url) | instance | url: url for the AJAX call | This method is typically not called externally. It is already called during the constructor call. |
| setRequestHeaders() | instance | (none) | This method is typically not called externally. It is called by the object itself to assemble the HTTP header that will be sent during the HTTP request. |
| onStateChange() | instance | (none) | This method is typically not called externally. It is called by the object itself when the AJAX call status changes. |
| respondToReadyState(readyState) | instance | readyState: state number (1 to 4) | This method is typically not called externally. It is called by the object itself when the AJAX call status changes. |
The options argument object
An important part of the AJAX operations is the options argument. There's no options class per se. Any object can be passed, as long as it has the expected properties. It is common to create anonymous objects just for the AJAX calls.
| Property | Type | Default | Description |
| method | String | 'post' | Method of the HTTP request |
| parameters | String | The url-formatted list of values passed to the request | |
| asynchronous | Boolean | true | Indicates if the AJAX call will be made asynchronously |
| postBody | String | undefined | Content passed to in the request's body in case of a HTTP POST |
| requestHeaders | Array | undefined | List of HTTP headers to be passed with the request. This list must have an even number of items, any odd item is the name of a custom header, and the following even item is the string value of that header. Example:my-header1', 'this is the value', 'my-other-header', 'another value''>'my-header1', 'this is the value', 'my-other-header', 'another value' |
| onXXXXXXXX | Function(XMLHttpRequest) | undefined | Custom function to be called when the respective event/status is reached during the AJAX call. Example var myOpts = {onComplete: showResponse, onLoaded: registerLoaded};. The function used will receive one argument, containing the XMLHttpRequest object that is carrying the AJAX operation. |
| onSuccess | Function(XMLHttpRequest) | undefined | Custom function to be called when the AJAX call completes successfully. The function used will receive one argument, containing the XMLHttpRequest object that is carrying the AJAX operation. |
| onFailure | Function(XMLHttpRequest) | undefined | Custom function to be called when the AJAX call completes with error. The function used will receive one argument, containing the XMLHttpRequest object that is carrying the AJAX operation. |
| insertion | Function(Object, String) | null | Function to be called to inject the returned text into an element. The function will be called with two arguments, the element object to be updated and the response text Applies only to Ajax.Updater objects. |
| evalScripts | Boolean | undefined, false | Determines if script blocks will be evaluated when the response arrives. Applies only to Ajax.Updater objects. |
| decay | Number | undefined, 1 | Determines the progressive slowdown in a Ajax.PeriodicalUpdater object refresh rate when the received response is the same as the last one. For example, if you use 2, after one of the refreshes produces the same result as the previous one, the object will wait twice as much time for the next refresh. If it repeats again, the object will wait four times as much, and so on. Leave it undefined or use 1 to avoid the slowdown. |
The Ajax.Updater class
Inherits from Ajax.Request
Used when the requested url returns HTML that you want to inject directly in a specific element of your page. You can also use this object when the url returns <script> blocks that will be evaluated upon arrival. Use the evalScripts option to work with scripts.
| Property | Type | Kind | Description |
| ScriptFragment | String | static | A regular expression to identify scripts |
| containers | Object | instance | This object contains two properties: containers.success will be used when the AJAX call succeeds, and containers.failure will be used otherwise. |
| Method | Kind | Arguments | Description |
| ctor(container, url, options) | constructor | container:this can be the id of an element, the element object itself, or an object with two properties - object.success element (or id) that will be used when the AJAX call succeeds, and object.failure element (or id) that will be used otherwise. url: the url to be fetched, options: AJAX options | Creates one instance of this object that will call the given url using the given options. |
| updateContent() | instance | (none) | This method is typically not called externally. It is called by the object itself when the response is received. It will update the appropriate element with the HTML or call the function passed in the insertion option. The function will be called with two arguments, the element to be updated and the response text. |
The Ajax.PeriodicalUpdater class
Inherits from Ajax.Base
This class repeatedly instantiates and uses an Ajax.Updater object to refresh an element on the page, or to perform any of the other tasks the Ajax.Updater can perform. Check the Ajax.Updater reference for more information.
| Property | Type | Kind | Description |
| container | Object | instance | This value will be passed straight to the Ajax.Updater's constructor. |
| url | String | instance | This value will be passed straight to the Ajax.Updater's constructor. |
| frequency | Number | instance | Interval (not frequency) between refreshes, in seconds. Defaults to 2 seconds. This number will be multiplied by the current decay when invoking theAjax.Updater object |
| decay | Number | instance | Keeps the current decay level applied when re-executing the task |
| updater | Ajax.Updater | instance | The most recently used Ajax.Updater object |
| timer | Object | instance | The JavaScript timer being used to notify the object when it is time for the next refresh. |
| Method | Kind | Arguments | Description |
| ctor(container, url, options) | constructor | container:this can be the id of an element, the element object itself, or an object with two properties - object.success element (or id) that will be used when the AJAX call succeeds, and object.failure element (or id) that will be used otherwise. url: the url to be fetched, options: AJAX options | Creates one instance of this object that will call the given url using the given options. |
| start() | instance | (none) | This method is typically not called externally. It is called by the object itself to start performing its periodical tasks. |
| stop() | instance | (none) | This method is typically not called externally. It is called by the object itself to stop performing its periodical tasks. |
| updateComplete() | instance | (none) | This method is typically not called externally. It is called by the currently used Ajax.Updater after if completes the request. It is used to schedule the next refresh. |
| onTimerEvent() | instance | (none) | This method is typically not called externally. It is called internally when it is time for the next update. |
Use Examples
Using the Ajax.Request class
If you are not using any helper library, you are probably writing a whole lot of code to create a XMLHttpRequest object and then track its progress asynchronously, then extract the response and process it. And consider yourself lucky if you do not have to support more than one
type of browser.
To assist with AJAX functionality, the library defines the Ajax.Request class.
Let's say you have an application that can communicate with the server via the url http://yoursever/app/get_sales?empID=1234&year=1998, which returns an XML response like the following.
<?xml version="1.0" encoding="utf-8" ?>
<ajax-response>
<response type="object" id="productDetails">
<monthly-sales>
<employee-sales>
<employee-id>1234</employee-id>
<year-month>1998-01</year-month>
<sales>$8,115.36</sales>
</employee-sales>
<employee-sales>
<employee-id>1234</employee-id>
<year-month>1998-02</year-month>
<sales>$11,147.51</sales>
</employee-sales>
</monthly-sales>
</response>
</ajax-response>
Talking to the server to retrieve this XML is pretty simple using an Ajax.Request object. The sample below shows how it can be done.
<script>
function searchSales() {
var empID = $F('lstEmployees');
var y = $F('lstYears');
var url = 'http://yoursever/app/get_sales';
var pars = 'empID=' + empID + '&year=' + y;
var myAjax = new Ajax.Request(
url,
{method: 'get', parameters: pars, onComplete: showResponse}
);
}
function showResponse(originalRequest) {
//put returned XML in the textarea
$('result').value = originalRequest.responseText;
}
</script>
<select id="lstEmployees" size="10" onchange="searchSales()">
<option value="5">Buchanan, Steven</option>
<option value="8">Callahan, Laura</option>
<option value="1">Davolio, Nancy</option>
</select>
<select id="lstYears" size="3" onchange="searchSales()">
<option selected="selected" value="1996">1996</option>
<option value="1997">1997</option>
<option value="1998">1998</option>
</select>
<br>
<textarea id=result cols=60 rows=10 ></textarea>
Can you see the second parameter passed to the constructor of the Ajax.Request object? The parameter {method: 'get', parameters: pars, onComplete: showResponse} represents an anonymous object in literal notation. What it means is that we are passing an object that has a property named method that contains the string 'get', another property named parameters that contains the querystring of the HTTP request, and an onComplete property/method containing the function showResponse.
There are a few other properties that you can define and populate in this object, like asynchronous, which can be true or false and determines if the AJAX call to the server will be made asynchronously (the default value is true.)
This parameter defines the options for the AJAX call. In our sample, we are calling the url in the first argument via a HTTP GET command, passing the querystring contained in the variable pars, and the Ajax.Request object will call the showResponse function when it finishes retrieving the response.
As you may know, the XMLHttpRequest reports progress during the HTTP call. This progress can inform four different stages: Loading, Loaded, Interactive, or Complete. You can make the Ajax.Request object call a custom function in any of these stages, the Complete being the most common one. To inform the function to the object, simply provide property/methods named onXXXXX in the request options, just like the onComplete from our example. The function you pass in will be called by the object with one argument, which will be the XMLHttpRequest object itself. You can then use this object to get the returned data and maybe check the status property, which will contain the HTTP result code of the call.
Two other interesting options can be used to process the results. We can specify the onSuccess option as a function to be called when the AJAX call executes without errors and, conversily, the onFailure option can be a function to be called when a server error happens. Just like the onXXXXX option functions, these two will also be called passing the XMLHttpRequest object that carried the AJAX call.
Our sample did not process the XML response in any interesting way. We just dumped the XML in the textarea. A typical usage of the response would probably find the desired information inside the XML and update some page elements, or maybe even some sort of XSLT transformation to produce HTML in the page.
For more complete explanations, see the Ajax.Request reference and the options reference.
Using the Ajax.Updater class
If you have a server endpoint that can return information already formatted in HTML, the library makes life even easier for you with the Ajax.Updater class. With it you just inform which element should be filled with the HTML returned from the AJAX call. An example speaks better that I can write.
<script>
function getHTML() {
var url = 'http://yourserver/app/getSomeHTML';
var pars = 'someParameter=ABC';
var myAjax = new Ajax.Updater('placeholder', url, {method: 'get', parameters: pars});
}
</script>
<input type=button value=GetHtml onclick="getHTML()">
<div id="placeholder"></div>
As you can see, the code is very similar to the previous example, with the exclusion of the onComplete function and the element id being passed in the constructor. Let's change the code a little bit to illustrate how it is possible to handle server errors on the client.
We will add more options to the call, specifying a function to capture error conditions. This is done using the onFailure option. We will also specify that the placeholder only gets populated in case of a successful operation. To achieve this we will change the first parameter from a simple element id to an object with two properties, success (to be used when everything goes OK) and failure (to be used when things go bad.) We will not be using the failure property in our example, just the reportError function in the onFailure option.
<script>
function getHTML() {
var url = 'http://yourserver/app/getSomeHTML';
var pars = 'someParameter=ABC';
var myAjax = new Ajax.Updater(
{success: 'placeholder'},
url,
{method: 'get', parameters: pars, onFailure: reportError}
);
}
function reportError(request) {
alert('Sorry. There was an error.');
}
</script>
<input type=button value=GetHtml onclick="getHTML()">
<div id="placeholder"></div>
If your server logic returns JavaScript code instead of HTML markup, the Ajax.Updater object can evaluate that JavaScript code. To get the object to treat the response as JavaScript, you simply add evalScripts: true; to the list of properties in the last argument of the object constructor.
For more complete explanations, see the Ajax.Updater reference and the options reference.