Don't know why but setting Default Formatter to ebsenp.prettier didn't work for me. But I found a similar command that worked.

1. ctrl + shift + p
2. Format document with
3. Configure default formatter
4. Choose prettier

I dont know the solution yet, but there are some info that may help.

• Basically, there are something wrong with the linter. ( https://github.com/prettier/prettier-vscode/issues/137 )

  And your may fix it by checking out this https://prettier.io/docs/en/integrating-with-linters.html ,

Actually, "format only selected code" is working on my end, I didnt do any fancy extra config.

• What you need to pay attention to is the "syntax tree"

  -- ie: dont blindly select across the scope (the bracket {}).

  @eg::

  • given

    function test() {
      let a = [1, 2, 3,          4];
    
      let b = [          1,2 ,3,4]; // select only this line
    
      return false
    }
    

  • if you only select::

    let b = [          1,2 ,3,4];
    

    then press ctrl+k, ctrl+f

    everything is fine

  • if you select across the bracket (the } for function scope)::

      let b = [          1,2 ,3,4]; // select only this line
    
      return false
    }
    

    then press ctrl+k, ctrl+f

    the whole thing in the bracket (the } for function scope) gets formatted

• the "syntax tree" in a class is a bit weird.

  -- ie: if you select the WHOLE function AA & format it -- codes inside another function BB will also get formatted...

  you may need to apply // prettier-ignore somewhere to prevent formatting

• prettier-ignore

  A JavaScript comment of // prettier-ignore will exclude the next node in the abstract syntax tree from formatting.

  https://prettier.io/docs/en/ignore.html

  • (note, it seems there is no ending tag for // prettier-ignore for Javascript (at current stage of Prettier))

  • for the meaning of a "syntax tree", see ex below

    • if you place it above the code line
      seems it applies to the item (the code) (-- which is a "syntax tree node") directly below ((empty lines not counted for)) the // prettier-ignore line
      -- eg-below: console.log("show a", a);, and ends there.

    • if you place it behind the code line (inline)
      seems it applies to the inline code only

• @for_your_case-do_this:

  const test = (a, b,          c) => {  
    // prettier-ignore
    console.log("show a",          a);  
    // prettier-ignore
    console.log("show b",     b);  
  }
  
  // or
  const test = (a, b,          c) => {  
    console.log("show a",          a); // prettier-ignore
    console.log("show b",     b); // prettier-ignore
  }