const inputs = [
  "dev build --from mybox2 -abc -q -v --image tm0:node -v -- bla1 bla2",
  "dev build --from mybox2 -abc valuec -q -v --image tm0:node mybox -v -- bla1 bla2",
];

let level = 1;
const commands = ["root", "build"];
function ref(...rest) {
  return commands
    .slice(0, level + 1)
    .concat(rest)
    .join(".");
}

console.log(ref("from"));