How to find duplicate values in a JavaScript array of objects, and output only unique values?

Question

I'm learning JS. Supposing I have the below array of objects:

var family = [
  {
    name: "Mike",
    age: 10
  },
  {
    name: "Matt"
    age: 13
  },
  {
    name: "Nancy",
    age: 15
  },
  {
    name: "Adam",
    age: 22
  },
  {
    name: "Jenny",
    age: 85
  },
  {
    name: "Nancy",
    age: 2
  },
  {
    name: "Carl",
    age: 40
  }
];

Notice that Nancy is showing up twice (changing only the age). Supposing I want to output only unique names. How do I output the above array of objects, without duplicates? ES6 answers more than welcome.

Related (couldn't find a good way for usage on objects):

• Remove Duplicates from JavaScript Array
• Easiest way to find duplicate values in a JavaScript array

EDIT Here's what I tried. It works well with strings but I can't figure how to make it work with objects:

family.reduce((a, b) => {
  if (a.indexOf(b) < 0 ) {
    a.push(b);
  }
  return a;
},[]);

Answer 1

You could use a Set in combination with Array#map and a spread operator ... in a single line.

Map returns an array with all names, which are going into the set initializer and then all values of the set are returned in an array.

var family = [{ name: "Mike", age: 10 }, { name: "Matt", age: 13 }, { name: "Nancy", age: 15 }, { name: "Adam", age: 22 }, { name: "Jenny", age: 85 }, { name: "Nancy", age: 2 }, { name: "Carl", age: 40 }],
    unique = [...new Set(family.map(a => a.name))];

console.log(unique);

For filtering and return only unique names, you can use Array#filter with Set.

var family = [{ name: "Mike", age: 10 }, { name: "Matt", age: 13 }, { name: "Nancy", age: 15 }, { name: "Adam", age: 22 }, { name: "Jenny", age: 85 }, { name: "Nancy", age: 2 }, { name: "Carl", age: 40 }],
    unique = family.filter((set => f => !set.has(f.name) && set.add(f.name))(new Set));

console.log(unique);