fx:True markup extension

The fx:True markup extension specifies the boolean true value.

In many cases, using the fx:True markup extension is not necessary. In a boolean assignment context, the text "true" is automatically converted to a boolean value.

Text assignment is target-typed, so the text "true" has no intrinsic boolean type. In particular, assigning value="true" to an Object property produces the string "true". Use {fx:True} when the value must be Boolean regardless of the assignment target.

As a method argument, the unquoted keyword true is a boolean literal. Quote it as 'true' to pass a string, or qualify it as a path such as :element.true to refer to a property named true.

Usage

<!-- Using the fx:True markup extension -->
<Button visible="{fx:True}"/>

<!-- Using type coercion -->
<Button visible="true"/>

<!-- The Object-valued property receives Boolean.TRUE, not the string "true" -->
<Button userData="{fx:True}"/>

<!-- Boolean and string literals as method arguments -->
<Button text="$String.format('%s / %s', true, 'true')"/>