Joomla! plugin example code Put these files into "plugin/system/sms" folder

sms.php

<?php

class plgSystemSms extends JPlugin
{
    /*
     * onAfterInitialise
     * onAfterRoute
     * onAfterDispatch
     * onAfterRender
     */

    public function onAfterRender()
    {
        $app = JFactory::getApplication();

        if ($app->isAdmin())
        {
            return;
        }

        $param = $this->params->get('a_foo_param', 'default_value');

        $body = JResponse::getBody();
        JResponse::setBody('$param:' . $param . $body);

        //jexit('<pre>'.$body.'</pre>');
    }

    public function onAfterDispatch()
    {
        $doc = JFactory::getDocument();
        $doc->addStyleSheet('system/sms/a.css');
        $doc->addScript('system/sms/a.js');

        $script = <<<JS
var nodeTest = document.getElementById('test');
JS;

        $doc->addScriptDeclaration($script);
        //var_dump($doc->_styleSheets);
        //var_dump($doc->_scripts);
    }
}

sms.xml

<?xml version="1.0" encoding="utf-8"?>
<extension version="3.1" type="plugin" group="content">
    <name>plg_system_sms</name>

    <config>
        <fields name="params">
            <fieldset name="basic">
                <field
                        name="a_foo_param"
                        type="text"
                        label="Foo"
                        description="這是描述"
                        default="烏拉阿拉~~~"
                        />
                <field
                        name="another_param"
                        type="list"
                        label="清單"
                        description="清單爹盟"
                        default="1"
                        >
                    <option value="0">???</option>
                    <option value="1">???</option>
                    <option value="2">????</option>
                </field>
                <field
                        name="another_param2"
                        type="radio"
                        label="清單2"
                        description="清單爹盟2"
                        default="2"
                        >
                    <option value="0">車馬炮</option>
                    <option value="1">將士象</option>
                    <option value="2">無名小卒</option>
                </field>
            </fieldset>

            <fieldset name="advanced">

            </fieldset>

            <fieldset name="foo">

            </fieldset>
        </fields>
    </config>
</extension>