Using the Bootstrap widget

Yii2 supports Bootstrap as a core feature. Bootstrap framework CSS and JavaScript files are injected by default in all pages and we could even use this feature to only apply CSS classes or call our own JavaScript function provided by Bootstrap.

However, Yii2 embeds Bootstrap as a widget, and we can access this framework's capabilities like any other widget.

The most used are:

Class name	Description
yii\bootstrap\Alert	This class renders an alert Bootstrap component
yii\bootstrap\Button	This class renders a Bootstrap button
yii\bootstrap\Dropdown	This class renders a Bootstrap drop-down menu component
yii\bootstrap\Nav	This class renders a nav HTML component
yii\bootstrap\NavBar	This class renders a navbar HTML component

For example, yii\bootstrap\Nav and yii\bootstrap\NavBar are used in the default main template.

This is an extract from the main layout view (in basic/views/layouts/main.php):

        <?php
            NavBar::begin([
       ...