default value on javascirpt

index.js

function defvalue(fn, v) {
  let ret;
  try{
    ret = fn();
  }catch(e){
    ret = v;
  }
  if(ret === undefine){
    ret = v;
  }
  return v;
}
// suppress TypeError: created_at of undefined is not defined
let date = defvalue(()=>res.body.foo.created_at, null);