conditional object spread

var cond = true;

var extraInfo = [
  {
    a: 11,
    b: 25
  },
  {
    a: 12,
    b: 34
  },
  {
    a: 1,
    c: 99
  }
];

var userInfo = [
  {
    z: 8
  },
  {
    z: 10
  },
  ...(cond ? extraInfo : [])
];

console.log( userInfo );