How to concat data into one object in JS?

Question

How to add new values to object in Javascript/Typescript?

I have this JSON:

{
   "firstname":"chris",
   "lastname":"bosh"
}

and this one:

{
   "login":"c.bosh",
   "email: "c.bosh@bosh.com"
}

how to concat this two object into one, like this:

{
   "firstname":"chris",
   "lastname":"bosh",
   "login":"c.bosh",
   "email: "c.bosh@bosh.com"
}