To perform .join on value in array of objects with JavaScript, we use map to map the array of object to an array of primitive values.
For instance, we write
const users = [
{ name: "Joe", age: 22 },
{ name: "Kevin", age: 24 },
{ name: "Peter", age: 21 },
];
const s = users.map((u) => u.name).join(", ");
to call users.map with a callback that gets the name property value from each object and return them in an array.
Then we call join to combine then into a string with commas.
