.. image:: https://raw.githubusercontent.com/score-framework/py.doc/master/docs/score-banner.png :target: http://score-framework.org

The SCORE Framework_ is a collection of harmonized python and javascript libraries for the development of large scale web projects. Powered by strg.at_.

.. _The SCORE Framework: http://score-framework.org .. _strg.at: http://strg.at

score.dom.state

.. _js_dom_state:

.. image:: https://travis-ci.org/score-framework/js.dom.state.svg?branch=master :target: https://travis-ci.org/score-framework/js.dom.state

This module implements a state machine for the DOM. When properly applied, this approach can provide rudimentary solutions for a vast range of use cases. Some examples include:

• accordions
• menus
• tabs

Quickstart

Note: You can read this quickstart along with its fiddle_.

.. _fiddle: https://jsfiddle.net/fjektzrv/

Let's create an accordion containing a delicious menu:

.. code-block:: html

<div id="menu">
    <div id="starters">
        <h1>Starters</h1>
        <ul class="state-content">
            <li>moules marinieres</li>
            <li>pate de foie gras</li>
            <li>beluga caviar</li>
            <li>eggs Benedictine</li>
            <li>tart de poireaux</li>
            <li>frogs' legs amandine</li>
            <li>oeufs de caille Richard Shepherd</li>
        </ul>
    </div>
    <div id="cheese">
        <h1>Cheese</h1>
        <ul class="state-content">
            <li>Red Windsor</li>
            <li>Stilton</li>
            <li>Gruyere</li>
            <li>Emmental</li>
            <li>Norwegian Jarlsberger</li>
            <li>Liptauer</li>
            <li>Lancashire</li>
            <li>White Stilton</li>
            <li>Danish Blue</li>
        </ul>
    </div>
    <div id="dessert">
        <h1>Dessert</h1>
        <ul class="state-content">
            <li>wafer-thin mint</li>
        </ul>
    </div>
</div>

We will first need to create a group for the states of the menu:

.. code-block:: javascript

var menu = new score.dom.state.Group(score.dom('#menu'));

This will add the CSS class score-state-group to the top-most #menu node. We can now create a state for each tab:

.. code-block:: javascript

menu.defineState('starters', score.dom('#starters'));
menu.defineState('cheese', score.dom('#cheese'));
menu.defineState('dessert', score.dom('#dessert'));

Each state node now has the additional CSS class score-state. The group will now make sure, that at any given time, at most one of these states is active. The active state will additionaly receive the class score-state--active. Let's show the starters:

.. code-block:: javascript

menu.show('starters');

The DOM now looks like this:

.. code-block:: html

<div id="menu" class="score-state-group score-state-group--starters">
    <div id="starters" class="score-state score-state--active">
        ...
    </div>
    <div id="cheese" class="score-state">
        ...
    </div>
    <div id="dessert" class="score-state">
        ...
    </div>
</div>

If we now switch to the cheese section (menu.show('cheese')), the DOM will instead look like the following:

.. code-block:: html

<div id="menu" class="score-state-group score-state-group--cheese">
    <div id="starters" class="score-state">
        ...
    </div>
    <div id="cheese" class="score-state score-state--active">
        ...
    </div>
    <div id="dessert" class="score-state">
        ...
    </div>
</div>

The example just needs a bit of styling to work:

.. code-block:: css

#menu .state-content {
    display: none;
}

#menu .score-state--active .state-content {
    display: block;
}

Details

State Objects

The examples in the Quickstart section use a simplified API, where states are defined with a function call on the group itself:

.. code-block:: javascript

var state = menu.defineState('starters', score.dom('#starters'));

This call actually creates a new State object and returns it. It is equivalent to the following:

.. code-block:: javascript

var state = new score.dom.state.State(menu, 'starters', score.dom('#starters'));

This is important to know, as it is possible to tweak a state's behaviour, as we will see in the next few sections.

State Transitions

Whenever a state group is ordered to load a certain state, it will perform a multi-step transitions from the active state to the requested state:

• Initialize the new state if it's loaded for the first time.
• Deactivate the current state (if there is one).
• Activate the requested state.

State objects have a function for each of these operations: _init, _activate and _deactivate. It is possible to create sub-classes of the State class to perform some tasks at these points:

.. code-block:: javascript

var CheeseState = score.oop.Class({
    __name__: 'CheeseState',
    __parent__: score.dom.state.State,

    _activate: function(self) {
        alert("Sorry, we're out of cheese");
    }

});

These functions may also return Promises, in which case the state transition is delayed until the promise is complete:

.. code-block:: javascript

var StartersState = score.oop.Class({
    __name__: 'StartersState',
    __parent__: score.dom.state.State,

    _deactivate: function(self) {
        // whoa, better eat up!
        return new Promise(function(resolve, reject) {
            window.setTimeout(resolve, 3600 * 1000);
        });
    }
});

The state above takes a full hour to deactivate, in which time the menu will refuse to perform any other state transitions (since a very long-lasting one is already in progress).

The Initialization can be used to perform some heavy-duty operations only when they are necessary (i.e. when the state is actually relevant). Loading the main courses asynchronously might look likethe following:

.. code-block:: javascript

var MainCoursesState = score.oop.Class({
    __name__: 'MainCoursesState',
    __parent__: score.dom.state.State,

    _init: function(self) {
        return score.ajax('/main-courses').then(function(courses) {
            var list = self.node.find('.state-content');
            courses.forEach(function(course) {
                list.append(score.dom.create('li').text(course));
            });
        });
    }
});

Events

The state objects support events for each of the above function definitions:

.. code-block:: javascript

menu.states.cheese.on('init', function() {
    // TODO: compile list of excuses
});

menu.states.dessert.on('deactivate', function() {
    // this handler may return false to indicate
    // that the transition should be canceled.
    console.log("Customer has died");
    return false;
});

The most important difference between the events and the specific methods is that events follow the usual rules of the score.oop module, which means that all event listeners need to be synchronous.

Acknowledgments

Many thanks to BrowserStack_ and Travis CI_ for providing automated tests for our open source projects! We wouldn't be able to maintain our high quality standards without them!

.. _BrowserStack: https://www.browserstack.com .. _Travis CI: https://travis-ci.org/

License

Copyright © 2015-2017 STRG.AT GmbH, Vienna, Austria

All files in and beneath this directory are part of The SCORE Framework. The SCORE Framework and all its parts are free software: you can redistribute them and/or modify them under the terms of the GNU Lesser General Public License version 3 as published by the Free Software Foundation which is in the file named COPYING.LESSER.txt.

The SCORE Framework and all its parts are distributed without any WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. For more details see the GNU Lesser General Public License.

If you have not received a copy of the GNU Lesser General Public License see http://www.gnu.org/licenses/.

The License-Agreement realised between you as Licensee and STRG.AT GmbH as Licenser including the issue of its valid conclusion and its pre- and post-contractual effects is governed by the laws of Austria. Any disputes concerning this License-Agreement including the issue of its valid conclusion and its pre- and post-contractual effects are exclusively decided by the competent court, in whose district STRG.AT GmbH has its registered seat, at the discretion of STRG.AT GmbH also the competent court, in whose district the Licensee has his registered seat, an establishment or assets.