NAME

WWW::Scripter - For scripting web sites that have scripts

VERSION

0.032 (alpha)

SYNOPSIS

use WWW::Scripter;
$w = new WWW::Scripter;

$w->use_plugin('Ajax');  # packaged separately

$w->get('http://some.site.com/that/relies/on/ajax');
$w->eval(' alert("Hello from JavaScript") ');
$w->document->getElementsByTagName('div')->[0]->....

$w->content; # returns the HTML content, possibly modified
             # by scripts

DESCRIPTION

This is a subclass of WWW::Mechanize that uses the W3C DOM and provides support for scripting.

No actual scripting engines are provided with WWW::Scripter, but are available as separate plugins. (See also the "SEE ALSO" section below.)

SINGLE VS MULTIPLE WINDOWS

There are two basic modes in which you can use WWW::Scripter:

If you only need a single virtual window (which is usually the case), use WWW::Scripter itself, as described below and in WWW::Mechanize.

For multiple windows, start with a window group (see WWW::Scripter::WindowGroup) and fetch the WWW::Scripter object via its active_window method before proceeding.

At any time you can attach an existing window (WWW::Scripter object) to a window group using the latter's attach method. You can also ->close a window to detach it from its window group and put it back in single-window mode.

These two modes affect the behaviour of a few methods (open, close, blur, focus) and hyperlinks and forms with explicit targets.

INTERFACE

See WWW::Mechanize for a vast list of methods that this module inherits. (See also the "Notes About WWW::Mechanize Methods", below.)

In addition to those, this module implements the well-known Window interface, providing also a few routines for attaching scripting engines and what-not.

In the descriptions below, $w refers to the WWW::Scripter object. You can think of it as short for either 'WWW::Scripter' or 'window'.

Constructor

my $w = new WWW::Scripter %args

The constructor accepts named arguments. There are only two that WWW::Scripter itself deals with directly. The rest are passed on to the superclass. See WWW::Mechanize and LWP::UserAgent for details on what other arguments the constructor accepts.

The two arguments are:

max_docs: The maximum number of document objects to keep in history (along with their corresponding request and response objects). If this is omitted, Mech's stack_depth + 1 will be used. This is off by one because stack_depth is the number of pages you can go back to, so it is one less than the number of recorded pages. max_docs considers 0 to be equivalent to infinity.
max_history: If the number of items in history exceeds max_docs, WWW::Scripter will still keep the request objects (so you can go back more than max_docs times and previously visited pages will reload). max_history restricts the total number of items in history (whether full document objects or just requests). 0 is equivalent to infinity.

The Window Interface

In addition to the methods listed here, see also HTML::DOM::View and HTML::DOM::EventTarget.

location

Returns the location object (see WWW::Scripter::Location). If you pass an argument, it sets the href attribute of the location object.

alert

confirm

prompt

Each of these calls the function assigned by one of the set_* methods below under "Window-Related Methods".

navigator

Returns the navigator object. See WWW::Scripter::Navigator.

screen

Returns the screen object. It currently has no features.

setTimeout ( $code_string, $ms );

setTimeout ( $coderef, $ms, @args );

This schedules the code to run after $ms milliseconds have elapsed, returning a number uniquely identifying the time-out. If the first argument is a coderef or an object with &{} overloading, it will be called as such. Otherwise, it is parsed as a string of JavaScript code. (If the JavaScript plugin is not loaded, it will be ignored.)

setInterval ( $code_string, $ms );

setInterval ( $coderef, $ms, @args );

This method is just like setTimeout, except that, when the code runs, it schedules it to run again after $ms milliseconds.

clearTimeout ( $timeout_id )

The cancels the time-out corresponding to the $timeout_id. This only works for those registered with setTimeout.

clearInterval ( $timer_id )

The cancels the timer corresponding to the $timer_id. This only works for those registered with setInterval.

open ( $url, $target, $features, $replace )

If $target is not specified or if there is no window or frame named $target, this methods opens the $url in a new window in multiple-window mode, or at the top-level window in single-window mode.

If there is a window or frame named $target, then the $url is opened in that window. If $replace is true, it replaces the current page.

A relative $url is resolved according to the base URL of the current window (the one that open is called on), not the $target.

The $features argument is ignored.

close

In multiple-window mode, this detaches this window from its window group. In single-window mode (when there is no window group) it goes back to the previous entry in history (so that it is the opposite of open).

focus

In multiple-window mode, this brings this window to the front. In single-window mode (when there is no window group) it does nothing.

blur

In multiple-window mode, this sends this window back one, if it is the frontmost window. In single-window mode (when there is no window group) it does nothing.

history

Returns the history object. See WWW::Scripter::History.

window

self

These two return the window object itself.

frames

Although the W3C DOM specifies that this return $w (the window itself), for efficiency's sake this returns a separate object which one can use as a hash or array reference to access its sub-frames. (The window object itself cannot be used that way.) The frames object (class WWW::Scripter::Frames) also has a window method that returns $w.

In list context a list of frames is returned.

length

Returns the number of frames. $w->length is equivalent to scalar @{$w->frames}.

top

Returns the 'top' window, which is the window itself if there are no frames.

parent

Returns the parent frame, if there is one, or the window object itself otherwise.

name

This returns the window's name, if applicable. For a frame, this comes from the frame element to which the window belongs. For a top-level window created by open, this is the name that was passed as the second argument.

scroll

scrollTo

scrollBy

These exist in case scripts try to call them. They don't do anything.

These methods are not part of the Window interface, but are closely related to the object's window behaviour.

set_alert_function

set_confirm_function

set_prompt_function

Use these to set the functions called by the above methods. There are no default confirm and prompt functions. The default alert prints to the currently selected file handle, with a line break tacked on the end.

check_timers

This evaluates the code associated with each timeout registered with the setTimeout method, if the appropriate interval has elapsed.

count_timers

This returns the number of timers currently registered.

wait_for_timers ( %args )

This method waits for any registered timers to finish (calling check_timers repeatedly in a loop). Its %args are as follows:

max_wait    Number indicating for how many seconds the loop
            should run before giving up and returning.
min_timers  Only run until this many timers are left, not until
            they have all finished.
interval    Number of seconds to wait before each iteration of
            the loop.  The default is .1.

Some websites have timers running constantly, that are never cleared. For these, you will usually need to set a value for min_timers (or max_wait) to avoid an infinite loop.

window_group

This returns the window group that owns this window. See "SINGLE VS MULTIPLE WINDOWS", above.

You can also pass an argument to set it, but you should only do so if you know what you are doing, as it does not update the window group's list. Consider using WWW::Scripter::WindowGroup's attach method (which itself uses this method).

find_target ( $name )

This finds the WWW::Scripter object (window or frame) in which a link will be opened.

If $name is not an empty string, it returns the window corresponding to $name.

If $name is the empty string or undefined, it returns the default target for this window, based on the first <base target> element.

If a named window cannot be found: in multiple-window mode, a new window is opened and returned; in single-window mode, undef is returned.

Methods for Fetching Images

fetch_images ( $new_val )

A boolean indicating whether images should be fetched. Some sites use images with special URLs as cookies and refuse to work if those images are not fetched. Most of the time, however, you probably want to leave this off, for speed's sake.

Setting this does not affect any pages that are already loaded.

image_handler ( $coderef )

A subroutine for handling any images that are fetched. The subroutine will be passed three arguments: 0) the WWW::Scripter object, 1) the image or input element and 2) the response object.

Methods for Plugins, Scripting, etc.

eval ( $code [, $scripting_language] )

Evaluates the $code passed to it. This method dies if there is no script handler registered for the $scripting_language.

use_plugin ( $plugin_name [, @options] )

This will automatically require() the plugin for you, and then initialise it. To pass extra options to the plugin after loading it, just use the same syntax again. This will return the plugin object if the plugin has one.

plugin ( $plugin_name )

This will return the plugin object, if it has one. Some plugins may provide this as a way to communicate directly with the plugin.

You can also use the return value as a boolean, to see whether a plugin is loaded.

dom_enabled ( $new_val )

This returns a boolean indicating whether HTML pages are parsed and turned into a DOM tree. It is true by default. You can disable HTML parsing by passing a false value. Of course, if you are using WWW::Scripter to begin with, you won't want to turn this off will you? Nevertheless, this is useful for fetching files behind the scenes when just the file contents are needed.

scripts_enabled ( $new_val )

This returns a boolean indicating whether scripts are enabled. It is true by default. You can disable scripts by passing a false value. When you disable scripts, event handlers are also disabled, as is the registration of event handlers by HTML event attributes.

script_handler ( $language_re, $object )

A script handler is a special object that knows how to run scripts in a particular language. Use this method to register such an object.

$language_re is a regular expression that will be matched against a scripting language name (from a 'language' HTML attribute) or MIME type (<script type=...). You can also use the special value 'default'.

$object is the script handler object. For its interface, see "SCRIPT HANDLERS", below.

class_info ( \%interfaces )

With this you can provide information for binding Perl classes to scripting languages, so that scripts can handle objects of those classes.

You should pass a hash ref that has the structure described in HTML::DOM::Interface, except that this method also accepts a _constructor hash element, which should be set to the name of the method to be called when the constructor function is called from the scripting language (e.g., _constructor => 'new') or a subroutine reference.

The return value is a list of all hashrefs passed to class_info so far plus a few that WWW::Scripter has by default (to support the DOM). You can call it without any arguments just to get that list.

Other Methods

forward: The equivalent of hitting the 'forward' button in a browser. This, of course, only works after back.
clear_history ( $including_current_page ): This clears the history, preventing back from working until after the next request, and freeing up some memory. If supplied with a true argument, it also clears the current page. It returns $w.
max_history
max_history ( $new_value )
max_docs
max_docs ( $new_value ): These two return what was passed to the constructor, optionally setting it.

Notes About WWW::Mechanize Methods

links

WWW::Scripter overrides the _extract_links method that links, find_link and follow_link use behind the scenes, to make it use the HTML DOM tree instead of the source code of the page.

This overridden method tries hard to match WWW::Mechanize as closely as possible, which means it includes link tags, (i)frames, and meta tags with http-equiv set to 'refresh'.

This is significantly different from $w->document->links, an HTML::DOM method that follows the W3C DOM spec and returns only 'a' and 'area' elements.

EVENTS

To trigger events (and event handlers), use the trigger_event method of the object on which you want to trigger it. For instance:

$w->trigger_event('resize');  # runs onresize handlers
$w->document->links->[0]->trigger_event('mouseover');
$w->current_form->trigger_event('submit');  # same as $w->submit

trigger_event accepts more arguments. See HTML::DOM and HTML::DOM::EventTarget for details.

CAVEATS

WWW::Scripter does not implement any event loop, so you have to call check_timers or wait_for_timers yourself to trigger any timeouts. If you set up a loop like this,

sleep 1, $w->check_timers  while $w->count_timers;

or if you use wait_for_timers, beware that these may cause an infinite loop if a timeout sets another timeout, or if a timer is registered with setInterval. You basically have to know what works with the pages you are browsing.

THE `%WindowInterface` HASH

The hash named %WWW::Scripter::WindowInterface lists the interface members for the window object. It follows the same format as hashes within %HTML::DOM::Interface, like this:

(
    alert => VOID|METHOD,
    confirm => BOOL|METHOD,
    ...
)

It only includes those methods listed above under "The Window Interface".

SCRIPT HANDLERS

This section is only of interest to those implementing scripting engines. If you are not writing one, skip this section (or just read it anyway).

A script handler object must provide the following methods:

eval ( $w, $code, $url, $line, $is_inline )

(where $w is the WWW::Scripter object)

This is supposed to run the $code passed to it. It must set $@ to a true value if there is an error.

event2sub ( $w, $elem, $event_name, $code, $url, $line )

This is called for each HTML event attribute (onclick, etc.). It should return a coderef that runs the $code.

If it could not create a code ref, it should return undef and put the error message, if any, in $@.

WRITING PLUGINS

Plugins are usually under the WWW::Scripter::Plugin:: namespace. If a plugin name has a hyphen (-) in it, the module name will contain a double colon (::). If, when you pass a plugin name to use_plugin or plugin, it has a double colon in its name, it will be treated as a fully-qualified module name (possibly) outside the usual plugin namespace. Here are some examples:

Plugin Name       Module Name
-----------       -----------
Chef              WWW::Scripter::Plugin::Chef
Man-Page          WWW::Scripter::Plugin::Man::Page
My::Odd::Plugin   My::Odd::Plugin

This module will need to have an init method, and possibly two more named options and clone, respectively:

init

init will be called as a class method the first time use_plugin is called for a particular plugin. The second argument ($_[1]) will be the WWW::Scripter object. The third argument will be an array ref of options (see "options", below).

It may return an object if the plugin has one.

options

When $w->use_plugin is called, if there are any arguments after the plugin name, then the plugin object's options method will be called with the options themselves as the arguments.

If a plugin does not provide an object, an error will be thrown if options are passed to use_plugin.

The init method can override this, however. When it is called, its third argument is a reference to an array containing the options passed to use_plugin. The contents of that same array will be used when options is called, so init can modify it and even prevent options from being called altogether, by emptying the array.

clone

When the WWW::Scripter object is cloned (via the clone method), every plugin that has a clone method (as determined by ->can('clone')), will also be cloned. The new clone of the WWW::Scripter object is passed as its argument.

If the plugin needs to record data pertinent to the current page, it can do so by associating them with the document or the request via a field hash. See Hash::Util::FieldHash and Hash::Util::FieldHash::Compat.

Handlers

See LWP's Handlers feature.

From within LWP's request_* and response_* handlers, you can call WWW::Scripter::abort to abort the request and prevent a new entry from being created in browser history. (The JavaScript plugin does this with javascript: URLs.)

WWW::Scripter will export this function upon request:

use WWW::Scripter qw[ abort ];

or you can call it with a fully qualified name:

WWW::Scripter::abort();

BUGS

This is still an unfinished work. There are probably scores of bugs crawling all over the place. Here are some that are known (apart from the fact that so many features are still missing):

There is no support for XHTML, but HTML::Parser can handle most XHTML pages anyway, so maybe this is not a problem.
There is nothing to prevent infinite recursion when frames have circular references.

To report a bug, please send an e-mail to bug-WWW-Scripter@rt.cpan.org or use the web interface at http://rt.cpan.org/.

PREREQUISITES

perl 5.8.3 or higher (5.8.4 or higher recommended)

HTML::DOM 0.045 or higher

LWP 5.77 or higher

URI

WWW::Mechanize 1.2 or higher

Tie::RefHash::Weak 0.08 or higher for perl 5.8.x.

AUTHOR & COPYRIGHT

This program is free software; you may redistribute or modify it (or both) under the same terms as perl.

CONFESSION

Some of the code in here was stolen from the immediate superclass, WWW::Mechanize, as were some of the tests and test data.

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