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TiddlyWiki5/editions/tw5.com/tiddlers/widgets/ActionLogWidget.tid
2026-01-05 16:36:49 +00:00

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caption: action-log
created: 20201114113318785
modified: 20260105121108063
tags: Widgets ActionWidgets [[Debugging Widgets]]
title: ActionLogWidget
type: text/vnd.tiddlywiki
! Introduction
<<.from-version "5.1.23">> The <<.wid action-log>> widget is an [[action widget|ActionWidgets]] that can be used to output debugging information to the [[JavaScript console|Web Developer Tools]] supported by most browsers. This can be useful to observe and debug the behavior within a sequence of actions.
When the action is invoked, the names and values of all [[attributes|Widget Attributes]] are logged to the JavaScript console.
```
<$action-log name=value />
```
ActionWidgets are used within triggering widgets such as the ButtonWidget.
<<.note """ For debugging outside of actions see [[LogWidget]]""">>
! Content and Attributes
The <<.wid action-log>> widget is invisible. Any content within it is ignored.
<<.from-version "5.4.0">> Any [[multi-valued variables|Multi-Valued Variables]] or attributes are logged as a list of values.
|!Attribute |!Description |
|<<.attr $$filter>>|(Optional) All variables whose name matches the [[Filter Expression]] will be logged |
|<<.attr $$message>> |(Optional) A message to display as the title of the information logged. Useful when several <<.wid action-log>> widgets are used in sequence |
|<<.attr $$all>> |(Optional) Set to <<.value yes>> to log all variables |
<<.note """ If `<$action-log />` is called without any attributes, all defined variables will be logged as if `$$all=yes` were set.""">>
<<.note """When logging [[Variable Attribute Values]], the body text of macros and procedures will be output as their value. Functions are evaluated and their first result is logged.""">>
! Examples
!! Basic Example
Log the value of variable <<.var name>>, the first result of the filter expression `[tag[Learning]]` and the value of field <<.field created>> of the current tiddler:
```
<$action-log name=<<name>> filter={{{ [tag[Learning]] }}} created={{!!created}} />
```
!! Example using <<.attr $$filter>> and <<.attr $$message>>
Log all core variables (which start with <<.var tv->>) with a table title:
```
<$action-log $$message="Core Variables" $$filter="[prefix[tv-]]" />
```
!! Widget Debugging
Change a misbehaving <<.wlink ActionSetFieldWidget>> widget to an <<.wid action-log>> widget to verify that <<.var currentTiddler>> and <<.var value>> match their expected values:
<<.tip """If an action widget is not behaving as expected it is often useful to temporarily change it to an <<.wid action-log>> widget so that the passed attributes can be verified.""">>
```
<$action-log $tiddler=<<currentTiddler>> $field="text" $value=<<value>> />
```
This application is the primary reason that the attributes of the <<.wid action-log>> widget are prefixed with two dollar signs instead of one. Otherwise, the attributes of the original widget could be interpreted as attributes to <<.wid action-log>> and lead to unintended consequences.
!! Example with Function
Log the <<.var tiddlerList>> function definition and its first evaluation result:
```
\function tiddlerList() [tag[Learning]]
<$action-log $$filter="[title[tiddlerList]]" value=<<tiddlerList>> />
```
<<.note """The values output with the <<.attr $$filter>> or <<.attr $$all>> attributes will only contain the definition of functions instead of their values, as the evaluation of many functions can lead to significant performance penalties.""">>