signatureHelp always return empty replies

[humanitiesNerd]

I'm using Emacs Eglot and I have a single .js file

The signatureHelp requests from the client are always replied to with empty replies

Not so with hover requests, they get filled replies

Here's an example

client-request (id:10) Wed Dec 26 16:07:29 2018:
(:jsonrpc "2.0" :id 10 :method "textDocument/signatureHelp" :params
      (:textDocument
       (:uri "file:///home/catonano/Progetti/albo/savedata.js")
       :position
       (:line 32 :character 6)))

server-reply (id:10) Wed Dec 26 16:07:30 2018:
(:jsonrpc "2.0" :id 10 :result
      (:signatures
       []
       :activeParameter 0 :activeSignature 0))

client-request (id:11) Wed Dec 26 16:07:29 2018:
(:jsonrpc "2.0" :id 11 :method "textDocument/hover" :params
      (:textDocument
       (:uri "file:///home/catonano/Progetti/albo/savedata.js")
       :position
       (:line 32 :character 6)))

server-reply (id:11) Wed Dec 26 16:07:30 2018:
(:jsonrpc "2.0" :id 11 :result
      (:contents
       [(:language "typescript" :value "const insertTable: (mydata: any) => void")
        "**const**"]
       :range
       (:start
        (:line 32 :character 6)
        :end
        (:line 32 :character 17))))

This happens when, with the cursor, I hover onto this function

const insertTable = (mydata) => {
    const queryText = "INSERT INTO films (id, titolo) VALUES ($1, $2)";        
    const values = [
        1,
        mydata
    ];
    pool.query(queryText, values)
    .then((res) => {
            pool.end();
        })
        .catch((err) => {
        console.log(err);
            pool.end();
        });
}

I installed the server with

npm install -g

Do I need to configure anything ?

Or is this expected ?

Thanks