Push values from multiple objects to array

Question

I would like to know the best way to push values from multiple objects to an array while keeping them unique.

For example:

let emails = [];
owners.map(data => {
 emails.push(data.mail)
})
members.map(data => {
 emails.push(data.mail)
})
console.log(emails) 

emails gets populated with the emails from each object, but they are duplicates. I know how to filter an array for duplicates, but I want to see more options for the above code. Thanks!

Answer 1

Using array spread combine both arrays to a single array, and map the array to an array of emails. Convert the array to a Set to remove duplicates, and spread back to array:

const members = [
 { mail: '[email protected]' },
 { mail: '[email protected]' },
];
const owners = [
 { mail: '[email protected]' },
 { mail: '[email protected]' },
];
const emails = [...new Set([...members, ...owners].map(data => data.mail))];
console.log(emails)

Answer 2

As Ori mentioned, use Set

const emails = new Set();
owners.map(data => {
 emails.add(data.mail)
})
members.map(data => {
 emails.add(data.mail)
})
console.log(Array.from(emails)) //if you need it back to array