# Class: ComboButton

## LuCI .ui. ComboButton

The `ComboButton` class implements a button element which can be expanded into a dropdown to chose from a set of different action choices.

UI widget instances are usually not supposed to be created by view code directly, instead they're implicitely created by `LuCI.form` when instantiating CBI forms.

This class is automatically instantiated as part of `LuCI.ui`. To use it in views, use `'require ui'` and refer to `ui.ComboButton`. To import it in external JavaScript, use `L.require("ui").then(...)` and access the `ComboButton` property of the class instance value.

#### new LuCI.ui.ComboButton(value, choices, options)

ui.js, line 1986

  Instantiate a combo button widget offering multiple action choices.

  Name | Type | Default | Description
  --- | --- | --- | ---
  `value` | string | Array.<string> | null | optional The initial input value(s).
  `choices` | Object.<string, *> |  | Object containing the selectable choices of the widget. The object keys serve as values for the different choices while the values are used as choice labels.
  `options` | LuCI.ui.ComboButton.InitOptions |  | optional Object describing the widget specific options to initialize the button.

### Extends

- LuCI.ui.Dropdown

### Methods

#### inherited addChoices(values, labels)

ui.js, line 1663

  Add new choices to the dropdown menu.

  This function adds further choices to an existing dropdown menu, ignoring choice values which are already present.

  Name | Type | Description
  --- | --- | ---
  `values` | Array.<string> | The choice values to add to the dropdown widget.
  `labels` | Object.<string, *> | The choice label values to use when adding dropdown choices. If no label is found for a particular choice value, the value itself is used as label text. Choice labels may be any valid value accepted by `LuCI.dom#content`.

#### inherited clearChoices(reset_value)

ui.js, line 1628

  Remove all existing choices from the dropdown menu.

  This function removes all preexisting dropdown choices from the widget, keeping only choices currently being selected unless `reset_values` is given, in which case all choices and deselected and removed.

  Name | Type | Default | Description
  --- | --- | --- | ---
  `reset_value` | boolean | false | optional If set to `true`, deselect and remove selected choices as well instead of keeping them.

#### inherited closeAllDropdowns()

ui.js, line 1696

  Close all open dropdown widgets in the current document.

#### inherited isChanged(){boolean}

ui.js, line 141

  Check whether the input value was altered by the user.

  ##### Returns:

  Type | Description
  --- | ---
  boolean | Returns `true` if the input value has been altered by the user or `false` if it is unchaged. Note that if the user modifies the initial value and changes it back to the original state, it is still reported as changed.

#### inherited isValid(){boolean}

ui.js, line 154

  Check whether the current input value is valid.

  ##### Returns:

  Type | Description
  --- | ---
  boolean | Returns `true` if the current input value is valid or `false` if it does not meet the validation constraints.

#### inherited registerEvents(targetNode, synevent, events)

ui.js, line 203

  Dispatch a custom (synthetic) event in response to received events.

  Sets up event handlers on the given target DOM node for the given event names that dispatch a custom event of the given type to the widget root DOM node.

  The primary purpose of this function is to set up a series of custom uniform standard events such as `widget-update`, `validation-success`, `validation-failure` etc. which are triggered by various different widget specific native DOM events.

  Name | Type | Description
  --- | --- | ---
  `targetNode` | Node | Specifies the DOM node on which the native event listeners should be registered.
  `synevent` | string | The name of the custom event to dispatch to the widget root DOM node.
  `events` | Array.<string> | The native DOM events for which event handlers should be registered.

#### inherited setChangeEvents(targetNode, events)

ui.js, line 271

  Setup listeners for native DOM events that may change the widget value.

  Sets up event handlers on the given target DOM node for the given event names which may cause the input value to change completely, such as `change` events in a select menu. In contrast to update events, such change events will not trigger input value validation but they may cause field dependencies to get re-evaluated and will mark the input widget as dirty.

  Name | Type | Description
  --- | --- | ---
  `targetNode` | Node | Specifies the DOM node on which the event listeners should be registered.
  `events` | string | repeatable The DOM events for which event handlers should be registered.

#### inherited setPlaceholder(value)

ui.js, line 113

  Set the current placeholder value of the input widget.

  Name | Type | Description
  --- | --- | ---
  `value` | string | Array.<string> | null | The placeholder to set for the input element. Only applicable to text inputs, not to radio buttons, selects or similar.

#### inherited setUpdateEvents(targetNode, events)

ui.js, line 228

  Setup listeners for native DOM events that may update the widget value.

  Sets up event handlers on the given target DOM node for the given event names which may cause the input value to update, such as `keyup` or `onclick` events. In contrast to change events, such update events will trigger input value validation.

  Name | Type | Description
  --- | --- | ---
  `targetNode` | Node | Specifies the DOM node on which the event listeners should be registered.
  `events` | string | repeatable The DOM events for which event handlers should be registered.

#### inherited triggerValidation()

ui.js, line 168

  Force validation of the current input value.

  Usually input validation is automatically triggered by various DOM events bound to the input widget. In some cases it is required though to manually trigger validation runs, e.g. when programmatically altering values.

### Type Definitions

#### LuCI.ui.ComboButton.InitOptionsLuCI.ui.Dropdown.InitOptions

  ComboButtons support the same properties as `Dropdown.InitOptions` but enforce specific values for some properties and add aditional button specific properties.

  ##### Properties:

  Name | Type | Argument | Default | Description
  --- | --- | --- | --- | ---
  `multiple` | boolean |  | false | Since ComboButtons never allow selecting multiple actions, this property is forcibly set to `false`.
  `create` | boolean |  | false | Since ComboButtons never allow creating custom choices, this property is forcibly set to `false`.
  `optional` | boolean |  | false | Since ComboButtons must always select one action, this property is forcibly set to `false`.

  `classes`

  Object.<string, string>

  <optional>

  Specifies a mapping of choice values to CSS class names. If an action choice is selected by the user and if a corresponding entry exists in the `classes` object, the class names corresponding to the selected value are set on the button element.

  This is useful to apply different button styles, such as colors, to the combined button depending on the selected action.

  `click` | function | <optional> |  | Specifies a handler function to invoke when the user clicks the button. This function will be called with the button DOM node as `this` context and receive the DOM click event as first as well as the selected action choice value as second argument.