three dots in js

// Extracts elements in Dict
let team = {
    lead: "Bob",
    num2: "Rob",
    num3: "Dog",
}
// team
{lead: "Bob", num2: "Rob", num3: "Dog"}

let students = {
    num1: "Andy",
    num4: "Ben",
    ...team
}
//students
{num1: "Andy", num4: "Ben", lead: "Bob", num2: "Rob", num3: "Dog"}const numbers1 = [1, 2, 3, 4, 5];const numbers2 = [ ...numbers1, 1, 2, 6,7,8]; // this will be [1, 2, 3, 4, 5, 1, 2, 6, 7, 8]this.setState(prevState => {
    return {foo: {...prevState.foo, a: "updated"}};
});