expression.md

Expression expression design

Supported usages

'{{ value }}' '100'

'{{ value.toUppercase() }}' 'ABC'

'Hello, {{ value }}!' 'Hello, world'

'{{ $listItem.name }} is {{ $listItem.age }} years old' 'Tom is 10 years old'

'{{ $listItem.name }} is in {{ root.listTitle }} list' 'Tom is in UserList list'

nested expressions

Expressions support nesting, which is useful in the context of lists and modules. E.g:

'{{ {{$listItem.value}}Input.value + {{$moduleId}}Fetch.value }}!'

The parser will eval and concatenate strings from the inside out.

some wrong usages

{{ [1,2,3] }}string (result will be '[Object Object]').

special keywords

$i $listItem and $moduleId are keywords, used in lists and modules.

error handling

When the expression cannot be parsed or an error is reported during the parsing process, the expression itself will be returned directly.