How to extend JSON language ?

[VikydZhang]

JSON language has no loader function.

[Vignesh Prakash]

@vikyd I think you can use semantic tokens provider API from monaco editor
This API is available from version 0.21.0 of monaco editor.
You can tweak this example from playground to make it work for JSON

[VikydZhang]

Only highlight by tokens provider is not enough.

I also want to make it format correctly.

Example, this my input JSON string:

{
  "a": {{myName}}
}

I want to highlight {{myName}}.

And I also want to format the JSON string.

Expected:

{
  "a": {{myName}}
}

But actually, it become:

{
      "a": {
            {myName
            }
      }
}

[Vignesh Prakash]

@vikyd This package is indented to extend the tokenizer to add custom syntax highlighting only.
And this package will work only if there is a loader method present for the particular language.

For adding custom formatting there are APIs like registerOnTypeFormattingEditProvider, DocumentRangeFormattingEditProvider

A little exploration in monaco editor documentation will help you achieve your case