JS how to return all the values in an object that share a key

roomCoder :

I have an object that holds some email addresses in a component. I want to pass that object to a service that I have, and store all the values that have the email key in a variable.

here is the object that I have

mEmails = [
  {
    id: 1,
    email: ''
  },
  {
    id: 2,
    email: ''
  },
  {
    id: 3,
    email: ''
  },
  {
    id: 4,
    email: ''
  }
];

saveEmails(form: NgForm) {
    this.mEmails[0].email = form.value[1];
    this.mEmails[1].email = form.value[2];
    this.mEmails[2].email = form.value[3];
    this.mEmails[3].email = form.value[4];
    console.log(this.mEmails);
    this.sessionService.emails.emit(this.mEmails);
  }

Now I retrieve the array in my Service like this.

   this.emails.subscribe(
        emails => {
          console.log(emails);

        });

the result is

0: Object { id: 1, email: "[email protected]" }
​
1: Object { id: 2, email: "[email protected]" }
​
2: Object { id: 3, email: "[email protected]" }
​
3: Object { id: 4, email: "[email protected]" }

Now I get the array but the desired result that I would like is for me to get the values in a variable that looks like this

const emails = ['[email protected]','[email protected]','[email protected]','[email protected]']

I could do this manually but getting the index and setting that to a variable but that is very ineficeient and no a great way to scale up in the future. I am looking for something that will sort through the array and the object and return all the values with the key 'email' and concat them together and join them with a ','

Anurag Srivastava :

Use the Array.map function:

let mEmails = [
  {
    id: 1,
    email: '[email protected]'
  },
  {
    id: 2,
    email: '[email protected]'
  },
  {
    id: 3,
    email: '[email protected]'
  },
  {
    id: 4,
    email: '[email protected]'
  }
];

console.log(mEmails.map(obj => obj.email))