JavaScript: Produce new array from .reduce(), with map- and filter-like transformation in one step.

reduce.js

// Produce new array from .reduce(), with map- and filter-like transformation in one step.

// Example data courtesy of http://elijahmanor.com/reducing-filter-and-map-down-to-reduce/
const doctors = [
  { number: 1,  actor: "William Hartnell",      begin: 1963, end: 1966 },
  { number: 2,  actor: "Patrick Troughton",     begin: 1966, end: 1969 },
  { number: 3,  actor: "Jon Pertwee",           begin: 1970, end: 1974 },
  { number: 4,  actor: "Tom Baker",             begin: 1974, end: 1981 },
  { number: 5,  actor: "Peter Davison",         begin: 1982, end: 1984 },
  { number: 6,  actor: "Colin Baker",           begin: 1984, end: 1986 },
  { number: 7,  actor: "Sylvester McCoy",       begin: 1987, end: 1989 },
  { number: 8,  actor: "Paul McGann",           begin: 1996, end: 1996 },
  { number: 9,  actor: "Christopher Eccleston", begin: 2005, end: 2005 },
  { number: 10, actor: "David Tennant",         begin: 2005, end: 2010 },
  { number: 11, actor: "Matt Smith",            begin: 2010, end: 2013 },
  { number: 12, actor: "Peter Capaldi",         begin: 2013, end: 2013 }    
];


// As in the link about combining JS arrays below, we can use .concat() to return a new array.
// https://davidwalsh.name/combining-js-arrays#concat
const newDoctors = doctors.reduce((memo, doctor) =>
  doctor.begin > 2000 ? // this serves as our `filter`
    memo.concat({ // this serves as our `map`
      doctorNumber: "#" + doctor.number,
      playedBy: doctor.actor,
      yearsPlayed: doctor.end - doctor.begin + 1
    }) : memo
, []);