Do not set title for the GNU Screen, because it beeps.

[elinks.git] / doc / smjs-scripting.txt

[[smjs-scripting]]
Scripting ELinks with ECMAScript
--------------------------------

As a user of ELinks, you can control its behaviour by writing scripts
in ECMAScript.  Unlike <<ecmascript,scripts in SCRIPT elements of
HTML>>, these user scripts run with all the permissions of your user
account, the same as with <<lua-scripting,Lua>>.  The object model is
very different too.

Support for ECMAScript user scripts was first added in ELinks 0.11.0.
The `configure` script enables it by default if the required SpiderMonkey
library has been installed, but you can disable it with `configure
\--disable-sm-scripting` or by <<CONFIG-SCRIPTING-SPIDERMONKEY,editing
features.conf>>.

WARNING: ECMAScript scripting is still a bit experimental: there seem to be
ways to crash ELinks with it, and the object model may change.  However, if
you don't have a `hooks.js` file, there is not much risk in enabling the
feature at compile time.

When ELinks starts up, it evaluates the ECMAScript file `hooks.js` in
your ELinks configuration directory (thus normally `~/.elinks/hooks.js`
on Unix-like systems), or if the file does not exist there, then in
the system-wide ELinks configuration directory (the location depends
on how ELinks was built, but `/etc/elinks/hooks.js` is typical).

In the ELinks source tree, the `contrib/smjs` directory contains some
examples about scripting ELinks with ECMAScript.  Please see the
`README` file in that directory for details.


[[smjs-global-object]]
Global Object
~~~~~~~~~~~~~

The global object provided to ECMAScript user scripts contains the standard
ECMAScript classes, as well as the following:


[[smjs-global-methods]]
Global Object Methods
^^^^^^^^^^^^^^^^^^^^^

[[smjs-global.do_file]] do_file(path)::
        Load and evaluate the file with the given path (string). For example:
+
--
----------------------------------------------------------------------
do_file("/home/me/.elinks/hooks.js");
----------------------------------------------------------------------

will reload your hooks file.

*Compatibility:* ELinks 0.11.0
--


[[smjs-global-properties]]
Global Object Properties
^^^^^^^^^^^^^^^^^^^^^^^^

[[smjs-global.elinks]] elinks (elinks)::
        A reference to the <<smjs-elinks-object,ELinks object>>.
+
*Compatibility:* ELinks 0.11.0


[[smjs-elinks-object]]
ELinks Object
~~~~~~~~~~~~~

The global <<smjs-global.elinks,'elinks'>> property refers to this object.


[[smjs-elinks-methods]]
ELinks Object Methods
^^^^^^^^^^^^^^^^^^^^^

[[smjs-elinks.alert]] elinks.alert(message)::
        Display the given message (string) in a message box. For example:
+
--
----------------------------------------------------------------------
elinks.alert("Hello, world!");
----------------------------------------------------------------------

will display a friendly greeting.

*Compatibility:* ELinks 0.11.0
--

[[smjs-elinks.execute]] elinks.execute(command)::
        Execute the given command (string) on the current terminal.
        For example:
+
--
----------------------------------------------------------------------
var quoted_uri = "'" + elinks.location.replace(/'/g, "'\\''") + "'";
elinks.execute("firefox " + quoted_uri);
----------------------------------------------------------------------

will run Firefox with the URI of the current document.

*Compatibility:* ELinks 0.12pre1

WARNING: One must be very careful with 'elinks.execute', because depending
on the OS, the command may be subject to interpretation by a command
shell language. When constructing the command string, be sure to quote
any dubious parts (such as the URI of the current document, as above).
--

[[smjs-elinks.load_uri]] elinks.load_uri(uri, callback)::
        Load the given URI (string). When the URI completes loading, ELinks
        calls the given callback (function). The callback is passed the
        <<smjs-cache_entry-object,cache object>> that corresponds to the URI.
        For example:
+
--
----------------------------------------------------------------------
elinks.load_uri("http://www.eldar.org/cgi-bin/fortune.pl?text_format=yes",
                function (cached) { elinks.alert(cached.content); });
----------------------------------------------------------------------

displays a fortune.

The <<smjs-cache_entry-object,cache object>> will not expire until after the
callback returns.

*Compatibility:* ELinks 0.12pre1
--


[[smjs-elinks-properties]]
ELinks Object Properties
^^^^^^^^^^^^^^^^^^^^^^^^

[[smjs-elinks.home]] elinks.home (string)::
        ELinks's ``home'' directory, where it stores its configuration files.
        Read-only. For example,
+
--
----------------------------------------------------------------------
do_file(elinks.home + "hooks.js");
----------------------------------------------------------------------

will reload your hooks file.

*Compatibility:* ELinks 0.11.0
--

[[smjs-elinks.location]] elinks.location (string)::
        The URI of the currently open document. This can be read to get a
        string with the URI or set to load a different document.
        For example,
+
--
----------------------------------------------------------------------
elinks.location = elinks.location + "/..";
----------------------------------------------------------------------

will go up a directory (if the URI doesn't end in a file).

*Compatibility:* ELinks 0.11.0
--

[[smjs-elinks.bookmarks]] elinks.bookmarks (hash)::
        This is a hash, the elements of which correspond to the bookmarks.
        One can delve into the bookmarks hierarchy in a reasonably nifty
        fashion, just by using standard ECMAScript syntax:
+
--
----------------------------------------------------------------------
elinks.bookmarks.x.children.y.children.z.children.foo.title
----------------------------------------------------------------------

gets the title of the bookmark titled ``foo'' under the folder ``z'',
which is a subfolder of ``y'', which is a subfolder of ``x''.

*Compatibility:* ELinks 0.11.0

[[smjs-bookmark-properties]]
A bookmark object has these properties:

[[smjs-bookmark.title]] item.title (string)::
        This is the title of the bookmark. It can be read and set.

[[smjs-bookmark.url]] item.url (string)::
        This is the URI of the bookmark. It can be read and set.

[[smjs-bookmark.children]] item.children (hash)::
        This is a hash, the elements of which are the bookmarks that
        are children to the item. It is read-only.
--

[[smjs-elinks.globhist]] elinks.globhist (hash)::
        This is a hash, the elements of which correspond to entries in ELinks's
        global history. The hash is indexed by URI. For example,
+
--
----------------------------------------------------------------------
elinks.globhist["file:///"]
----------------------------------------------------------------------

will get you the history item for your root directory.

*Compatibility:* ELinks 0.12pre1

[[smjs-global_history_item-properties]]
A history item has these properties:

[[smjs-global_history_item.title]] item.title (string)::
        This is the title of the history item. It can be read and set.

[[smjs-global_history_item.url]] item.url (string)::
        This is the URI of the history item. It can be read and set.

[[smjs-global_history_item.last_visit]] item.last_visit (number)::
        This is the UNIX time of the last visit time for the item. UNIX time
        is the number of seconds that have passed between the UNIX epoch
        (which is 1970-01-01 00:00:00 UTC) and the represented time. Note that
        this is 'seconds' since the epoch, whereas ECMAScript likes to use
        'milliseconds' since the epoch. This property can be set or read.
--

[[smjs-elinks.action]] elinks.action (hash)::
        This hash lets you call the built-in actions of ELinks.  For example,
        you can call `elinks.action.auth_manager()` to open the authentication
        manager.  The names of the actions are the same as in elinks.conf or
        in the keybinding manager, except they have underscores instead of
        dashes in order to make them valid ECMAScript identifiers.
+
--
*Compatibility:* ELinks 0.12pre1

NOTE: When you read an action function from this hash, ELinks binds it to the
current tab; any later calls to the function affect that tab.  This may be
changed in a future version.  It is safest to call the function right away,
rather than save it in a variable and call it later.
--

[[smjs-elinks.keymaps]] elinks.keymaps (hash)::
        This is a hash, the elements of which correspond to ELinks's keymaps.
        Currently, there are three: 'elinks.keymaps.main', 'elinks.keymaps.edit',
        and 'elinks.keymaps.menu'. These elements are also hashes, the elements of
        which correspond to bindings. For example, `elinks.keymaps.main["q"]` is
        the binding to the ``q'' key in the main map. These bindings can be read,
        to get the name of the action to which the key is bound, or set to one of:
+
--
- A string with the name of the ELinks action.
- A function, which will thenceforth be called when the key is pressed.
- The string `"none"`, to unbind the key.  You can also use the `null`
  value for this purpose, but that crashes ELinks 0.11.4 and 0.12pre1
  (http://bugzilla.elinks.cz/show_bug.cgi?id=1027[bug 1027]),
  so it may be best to use the string for now.
--
+
--
For example,

----------------------------------------------------------------------
elinks.keymaps.main["!"] = function () { elinks.alert("Hello!"); }
----------------------------------------------------------------------

binds the ``!'' key in the main map to a function that displays a friendly
alert.

----------------------------------------------------------------------
elinks.keymaps.main["/"] = "search-typeahead-text";
----------------------------------------------------------------------

changes the ``/'' key to use the nice typeahead search function instead of
opening that ugly old search dialogue box.

*Compatibility:* ELinks 0.11.0, unless you use `null`.

NOTE: Do not read a function from <<smjs-elinks.action,'elinks.action'>>,
e.g. `elinks.action.search_typeahead_text`, and place it in a keymap.
ELinks binds such functions to the current tab when the script reads
them from 'elinks.action', so they will not work right in other tabs.
Use the name of the action instead.
--

[[smjs-elinks.vs]] elinks.vs (view_state)::
        This property refers to the <<smjs-view_state-object,view-state
        object>> for the current document, if any.
+
*Compatibility:* ELinks 0.12pre1


[[smjs-elinks-hooks]]
ELinks Object Hooks
^^^^^^^^^^^^^^^^^^^

These are actually properties, but a special case: one assigns functions
to them, which functions are called at certain events.

In the ELinks source tree, `contrib/smjs/hooks.js` provides a mechanism
with which multiple scripts can add their functions to the same hooks.
Please see `contrib/smjs/README` for details.

[[smjs-elinks.preformat_html]] elinks.preformat_html(cached, vs)::
        This function is called every time a document is loaded, before the
        document is actually rendered, to give scripts the opportunity to
        modify it. The first parameter is the <<smjs-cache_entry-object,cache
        object>> and the second is the <<smjs-view_state-object,view-state
        object>>.
+
--
The <<smjs-cache_entry-object,cache object>> will not expire until after this
function returns.

*Compatibility:* ELinks 0.11.1 as described.  ELinks 0.11.0 did not provide
the 'vs' argument.
--

[[smjs-elinks.goto_url_hook]] elinks.goto_url_hook(url)::
        This function is called every time the user enters something in the
        'Go to URL' box. The url (string) can be modified or not, and the
        returned string is substituted for what the user entered.  If the
        value `false` is returned, the URL is not changed and further hooks
        in ELinks are not run.
+
*Compatibility:* ELinks 0.11.0

[[smjs-elinks.follow_url_hook]] elinks.follow_url_hook(url)::
        This function is called every time the user tries to load a document,
        whether by following a link, by entering a URI in the Go to URL box,
        by setting <<smjs-elinks.location,'elinks.location'>>, or whatever.
        It behaves the same as <<smjs-elinks.goto_url_hook,'elinks.goto_url_hook'>>
        above.
+
*Compatibility:* ELinks 0.11.0


[[smjs-cache_entry-object]]
Cache Object
~~~~~~~~~~~~

The cache object mentioned in the descriptions of
<<smjs-elinks.load_uri,'elinks.load_uri'>> and
<<smjs-elinks.preformat_html,'elinks.preformat_html'>> is a wrapper for the
internal ELinks cache object.  ELinks passes the ECMAScript cache object as an
argument to your ECMAScript function, and keeps the corresponding document in
the cache until the function returns.  After that, ELinks may remove the
document from the cache, even if the function has saved the cache object to
some global variable.  Such an expired cache object does not work but it does
not crash ELinks either.

*Compatibility:* ELinks 0.11.0


[[smjs-cache_entry-properties]]
Cache Object Properties
^^^^^^^^^^^^^^^^^^^^^^^

[[smjs-cache_entry.content]] cached.content (string)::
        This is the content received from the server. It can be read and set.

[[smjs-cache_entry.type]] cached.type (string)::
        This is the MIME type of the cache entry. It can be read and set.

[[smjs-cache_entry.length]] cached.length (number)::
        This is the length of cached.content. It is read-only.

[[smjs-cache_entry.head]] cached.head (string)::
        This is the header received from the server. It can be read and set.

[[smjs-cache_entry.uri]] cached.uri (string)::
        This is the URI of the cache entry. It is read-only.


[[smjs-view_state-object]]
View-state Object
~~~~~~~~~~~~~~~~~

The view-state object mentioned in the descriptions of
<<smjs-elinks.preformat_html,'elinks.preformat_html'>> and
<<smjs-elinks.vs,'elinks.vs'>> is a wrapper for the internal ELinks view_state
object.  The view state holds information on how the current document is being
displayed.

*Compatibility:* ELinks 0.11.1


[[smjs-view_state-properties]]
View-state Object Properties
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[[smjs.view_state.plain]] vs.plain (boolean)::
        Whether the current document is rendered as HTML or displayed
        as plaintext. This can be read and set.

[[smjs.view_state.uri]] vs.uri (string)::
        This is the URI of the current document. It is read-only.