Placeholder

API reference › Bootstrap 6 › Placeholder

class	`yii2\extensions\bootstrap6\Placeholder`
Extends	`Widget` » `yii\base\Widget` » `yii\base\Component` » `yii\base\BaseObject`
Implements	`yii\base\ViewContextInterface`, `yii\base\Configurable`
Uses traits	`AttributesTrait`, `BootstrapWidgetTrait`
Source	`src/Placeholder.php`

Renders a Bootstrap loading placeholder (skeleton) element.

Properties

Property	Type	Description	Defined by
`$animation`	`string\|null`	Loading animation (`wave`, `pulse`, or `glow`), or `null` for a static placeholder. Default: `null`.	`Placeholder`
`$autoIdPrefix` static	`string`	The prefix to the automatically generated widget IDs. Default: `'w'`.	`yii\base\Widget`
`$behaviors` read-only	`array<yii\base\Behavior<static>>`	List of behaviors attached to this component.	`yii\base\Component`
`$clientEvents`	`array<string,` `yii\web\JsExpression\|string>`	Event handlers attached to the widget element, as event name => JavaScript handler source. Default: `[]`.	`BootstrapWidgetTrait`
`$clientOptions`	`array<string, mixed>\|false`	Options passed to the plugin constructor, or `false` to skip the JavaScript initialization. Default: `[]`.	`BootstrapWidgetTrait`
`$container`	`bool`	Whether to wrap the placeholder in a container element that carries the animation class. Default: `false`.	`Placeholder`
`$containerOptions`	`array<string, mixed>`	HTML attributes of the container tag; the `tag` option sets the tag name (default `p`). Default: `[]`.	`Placeholder`
`$id`	`string`	Id of the widget.	`yii\base\Widget`
`$options`	`array<string, mixed>`	HTML attributes of the widget container tag. Default: `[]`.	`Widget`
`$size`	`yii2\extensions\bootstrap6\enum\Size\|string\|null`	Size modifier rendered as the `placeholder-{value}` class (`xs`, `sm`, or `lg`), or `null` for the default. Default: `null`.	`Placeholder`
`$tagName`	`string`	Tag name of the placeholder element. Default: `'span'`.	`Placeholder`
`$theme`	`yii2\extensions\bootstrap6\enum\Theme\|string\|null`	Theme color rendered as the `bg-{value}` background utility, or `null` to use the current color. Default: `null`.	`Placeholder`
`$view`	`yii\web\View`	The view object that can be used to render views or view files.	`yii\base\Widget`
`$viewPath` read-only	`string`	The directory containing the view files for this widget.	`yii\base\Widget`
`$width`	`int\|string\|null`	Width as a grid column count rendered as `col-{value}`, a width class such as `w-75`, or `null` to omit it. Default: `null`.	`Placeholder`

Methods

Method	Description	Defined by
`__construct()`	Constructor.	`yii\base\BaseObject`
`__call()`	Calls the named method which is not a class method.	`yii\base\Component`
`__clone()`	This method is called after the object is created by cloning an existing one.	`yii\base\Component`
`__get()`	Returns the value of a component property.	`yii\base\Component`
`__isset()`	Checks if a property is set, i.e. defined and not null.	`yii\base\Component`
`__set()`	Sets the value of a component property.	`yii\base\Component`
`__unset()`	Sets a component property to be null.	`yii\base\Component`
`addAttributes()`	Adds a set of HTML attributes; attributes already set with the same name are replaced.	`AttributesTrait`
`addClass()`	Adds one or more CSS classes to the existing classes; duplicated classes are collapsed.	`AttributesTrait`
`addCssStyle()`	Adds CSS style properties to the `style` attribute.	`AttributesTrait`
`afterRun()`	This method is invoked right after a widget is executed.	`yii\base\Widget`
`attachBehavior()`	Attaches a behavior to this component.	`yii\base\Component`
`attachBehaviors()`	Attaches a list of behaviors to the component.	`yii\base\Component`
`attribute()`	Sets an HTML attribute value.	`AttributesTrait`
`beforeRun()`	This method is invoked right before the widget is executed.	`yii\base\Widget`
`begin()` static	Begins a widget.	`yii\base\Widget`
`behaviors()`	Returns a list of behaviors that this component should behave as.	`yii\base\Component`
`canGetProperty()`	Returns a value indicating whether a property can be read.	`yii\base\Component`
`canSetProperty()`	Returns a value indicating whether a property can be set.	`yii\base\Component`
`class()`	Replaces the existing CSS classes with the specified ones.	`AttributesTrait`
`className()` static	Returns the fully qualified name of this class.	`yii\base\BaseObject`
`detachBehavior()`	Detaches a behavior from the component.	`yii\base\Component`
`detachBehaviors()`	Detaches all behaviors from the component.	`yii\base\Component`
`end()` static	Ends a widget.	`yii\base\Widget`
`ensureBehaviors()`	Makes sure that the behaviors declared in `behaviors()` are attached to this component.	`yii\base\Component`
`getBehavior()`	Returns the named behavior object.	`yii\base\Component`
`getBehaviors()`	Returns all behaviors attached to this component.	`yii\base\Component`
`getId()`	Returns the ID of the widget.	`yii\base\Widget`
`getView()`	Returns the view object that can be used to render views or view files.	`yii\base\Widget`
`getViewPath()`	Returns the directory containing the view files for this widget.	`yii\base\Widget`
`hasEventHandlers()`	Returns a value indicating whether there is any handler attached to the named event.	`yii\base\Component`
`hasMethod()`	Returns a value indicating whether a method is defined.	`yii\base\Component`
`hasProperty()`	Returns a value indicating whether a property is defined for this component.	`yii\base\Component`
`init()`	Initializes the widget and validates `$animation`, `$size`, and `$theme`.	`Placeholder`
`off()`	Detaches an existing event handler from this component.	`yii\base\Component`
`on()`	Attaches an event handler to an event.	`yii\base\Component`
`render()`	Renders a view.	`yii\base\Widget`
`renderFile()`	Renders a view file.	`yii\base\Widget`
`run()`		`Placeholder`
`setId()`	Sets the ID of the widget.	`yii\base\Widget`
`setView()`	Sets the view object to be used by this widget.	`yii\base\Widget`
`trigger()`	Triggers an event.	`yii\base\Component`
`widget()` static	Creates a widget instance and runs it.	`yii\base\Widget`
`pluginInitialization()` protected	Returns the JavaScript that initializes a plugin with its normalized constructor options.	`BootstrapWidgetTrait`
`registerClientEvents()` protected	Registers the JavaScript event handlers listed in `$clientEvents` at `View::POS_END`.	`BootstrapWidgetTrait`
`registerPlugin()` protected	Registers the plugin asset, the plugin initialization when needed, and the `$clientEvents`.	`BootstrapWidgetTrait`

Events

Event	Type	Description	Defined by
`EVENT_INIT`	`yii\base\Event`	An event that is triggered when the widget is initialized via `init()`. Event name: `'init'`. Available since 2.0.11.	`yii\base\Widget`
`EVENT_BEFORE_RUN`	`yii\base\WidgetEvent`	An event raised right before executing a widget. Event name: `'beforeRun'`. Available since 2.0.11.	`yii\base\Widget`
`EVENT_AFTER_RUN`	`yii\base\WidgetEvent`	An event raised right after executing a widget. Event name: `'afterRun'`. Available since 2.0.11.	`yii\base\Widget`

Constants

Constant	Value	Description	Defined by
`ANIMATIONS`	`['glow', 'pulse', 'wave']`	Animations rendered as the `placeholder-{animation}` class.	`Placeholder`

Property details

$animation

public string|null $animation = null

Loading animation (wave, pulse, or glow), or null for a static placeholder.

The pulse and glow animations apply to descendant placeholders only, so they require $container.

Method details

init()

public function init(): void

Initializes the widget and validates $animation, $size, and $theme.

Throws

yii\base\InvalidConfigException: if $animation, $size, or $theme is not supported.

run()

public function run(): string

Returns

string