The Monaco Editor is a browser-based code editor, which also powers Microsoft VS Code. Thanks to IntelliSense features you can get suggestions by pressing Ctrl + Space and you will find some code hinting. A red line marks code errors like missing commas or unnecessary ones.
The Monaco Editor is used for JSON configurations e.g.
Filter Query configuration
Channel Filter configuration
Display Pattern configuration
Business Rule JSON configuration
Mail Template configuration
Different value configurations e.g. calculated values for text fields, or default values in business rules updating field values.
Using IntelliSense
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Intellisense will give you suggestions when you write your filter or code, so you get some assistance:
In an empty field press Control + Space to see how to start the code
Press Control + Space inside the quotation marks of a property to see possible values
In tagbox filter configuration you will see all available filters when choosing kind {"kind": ""},
See all available fields and their correct path: {"field": ""},
Create tagbox filter
Click into an empty field
Control + Space, to get suggestions
Choose "New object" in curly brackets (by just pressing enter)
Control + Space and choose: Kind
The first available filter (AndFilter) is added, remove this
Control + Space → now you get a selection of filters available
Choose a Filter, type a comma and enter
Control + Space will now show you all needed attributes of that filter