caption: button
created: 20131024141900000
modified: 20201108183908170
tags: Widgets
title: ButtonWidget
type: text/vnd.tiddlywiki

! Introduction

The button widget displays an HTML `<button>` element that can perform a combination of optional actions when clicked:

* Executing any ActionWidgets passed in the `actions` attribute
* Executing any ActionWidgets that are immediate children of the button widget
* Execute any integrated actions:
** Navigate to a specified tiddler
** Dispatch a user defined [[widget message|Messages]]
** Trigger a user defined [[popup|PopupMechanism]]
** Assign new text to a specified tiddler

The integrated actions are provided as a shortcut for invoking common actions. The same functionality is available via ActionWidgets, with the exception of the support for highlighting selected popups.

! Content and Attributes

The content of the `<$button>` widget is displayed within the button.

|!Attribute |!Description |
|actions |A string containing ActionWidgets to be triggered when the key combination is detected. <<.from-version "5.1.23">> the <<.def "modifier">> variable lists the modifier keys that are pressed when the action is invoked. The possible modifiers are ''ctrl'', ''ctrl-alt'', ''ctrl-shift'', ''alt'', ''alt-shift'', ''shift'' and ''ctrl-alt-shift'' |
|to |The title of the tiddler to navigate to |
|message |The name of the [[widget message|Messages]] to send when the button is clicked |
|param |The optional parameter to the message |
|set |A TextReference to which a new value will be assigned |
|setTitle |A title to which a new value will be assigned, ''without'' TextReference. Gets preferred over <<.attr set>> |
|setField |A ''field name'' to which the new value will be assigned, if the attribute <<.attr setTitle>> is present. Defaults to the ''text'' field |
|setIndex |An ''index'' to which the new value will be assigned, if the attribute <<.attr setTitle>> is present |
|setTo |The new value to assign to the TextReference identified in the `set` attribute or the text field / the field specified through <<.attr setField>> / the index specified through <<.attr setIndex>> of the title given through <<.attr setTitle>> |
|selectedClass |An optional additional CSS class to be assigned if the popup is triggered or the tiddler specified in <<.attr set>> already has the value specified in <<.attr setTo>>  |
|default |Default value if <<.attr set>> tiddler is missing for testing against <<.attr setTo>> to determine <<.attr selectedClass>> |
|popup |Title of a state tiddler for a popup that is toggled when the button is clicked. See PopupMechanism for details |
|popupTitle |Title of a state tiddler for a popup that is toggled when the button is clicked. In difference to the <<.attr popup>> attribute, ''no'' TextReference is used. See PopupMechanism for details |
|aria-label |Optional [[Accessibility]] label |
|tooltip |Optional tooltip |
|class |An optional CSS class name to be assigned to the HTML element|
|style |An optional CSS style attribute to be assigned to the HTML element |
|tag |An optional html tag to use instead of the default "button" |
|dragTiddler |An optional tiddler title making the button draggable and identifying the payload tiddler. See DraggableWidget for details |
|dragFilter |An optional filter making the button draggable and identifying the list of payload tiddlers. See DraggableWidget for details |
|tabindex |Sets the `tabindex` attribute of the button to the given value |
|disabled|<<.from-version "5.1.23">> Optional, disables the button if set to "yes". Defaults to "no"|

''Note:'' In almost all other cases where a TextReference is used as a widget attribute, it will be placed between curly brackets, to [[transclude|Transclusion in WikiText]] the value currently stored there. However, when we use a TextReference as the value of a button widget's <<.attr set>> attribute, we are referencing //the storage location itself//, rather than the value stored there, so we do ''not'' use curly brackets there. //Example:// we could code a button widget that sets the `caption` field of TiddlerA to be the same as that of TiddlerB as:

<<.tip """<$macrocall $name=".from-version" version="5.1.18"/> <$macrocall $name=".attr" _="setTitle"/>, <$macrocall $name=".attr" _="setField"/> and <$macrocall $name=".attr" _="setIndex"/> attributes allow specifying Tiddler states ''directly'', without interpreting them as [[TextReferences|TextReference]].
This is useful for edge-cases where titles may contain characters that are used to denote Tiddler fields or indices (`!!`, `##`)""">>

```
<$button set="TiddlerA!!caption" setTo={{TiddlerB!!caption}} >

Press me!

</$button>
```

''Tip:'' Set ''class'' to `tc-btn-invisible tc-tiddlylink` to have a button look like an internal link.