insert values in array format for key in object in JavaScript

Question

I am trying to convert an array(with email addresses) in to object. How to insert values in value array for one key?

 var list = [ "john@yahoo.com", "rami@gmail.com", "josh@yahoo.com", "bale@gmail.com" ]; (function() { var obj1 = {}; for (var a = 0, b = list.length; b > a; a++) { var str = list[a].split("@"); var arr = []; arr.push(str[0]); if (!(str[1] in obj1)) { obj1[str[1]] = []; //arr.push(str[0])]; } Object.values(obj1[str[1]]).push(str[0]) }; console.log(obj1); })(); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 

expected output

    {
    "gmail.com" : [3],//1+1+1
    "yahoo.com" : [4]//1+1+1+1
    }

I also want to add like

  { "gmail.com" : [3],//1+1+1 "yahoo.com" : [4]//1+1+1+1 } 

Answer 1

 var list = [ "john@yahoo.com", "rami@gmail.com", "josh@yahoo.com", "bale@gmail.com" ]; obj = {}; list.map(x => x.split('@')[1]).forEach(x => obj[x] = []) list.forEach(email => obj[email.split('@')[1]].push(email)) console.log(obj) /* { "yahoo.com": [ "john@yahoo.com", "josh@yahoo.com" ], "gmail.com": [ "rami@gmail.com", "bale@gmail.com" ] } */ 

Explanation : Created a blank object obj . Then I iterated on list and retrieved all the domains by list.map(x => x.split('@')[1]) .

With domains in hand, I setup-ed the object to have the structure { 'yahoo.com': [], 'gmail.com': [] }

Then I iterated on list again and added the email if domain contained the corresponding part, giving resultant object.

Edit : It can also be done in single iteration this way:

 var list = [ "john@yahoo.com", "rami@gmail.com", "josh@yahoo.com", "bale@gmail.com" ] obj = {} list.forEach(email => { let domain = email.split('@')[1] if (!obj[domain]) obj[domain] = [] if (obj[domain].indexOf(email) < 0) obj[domain].push(email) }) console.log(obj) 

Here, I'm iterating on list, extracting the domain, setting up the key with [] if it doens't exist and then pushing the email into that. It also makes sure that no duplicate emails are pushed.

Answer 2

You can simply push the values in the array if the key is found in object otherwise add the array

 var list = [ "john@yahoo.com", "rami@gmail.com", "josh@yahoo.com", "bale@gmail.com" ]; (function() { var obj1 = {}; for (var a = 0; a < list.length; a++) { var str = list[a].split("@"); if(obj1[str[1]]) { obj1[str[1]].push(list[a]) } else { obj1[str[1]] = [list[a]]; //arr.push(str[0])]; } }; console.log(obj1); })(); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 

Answer 3

Your code is almost correct, there is just a minor bug, change your line:

Object.values(obj1[str[1]]).push(str[0])

To

obj1[str[1]].push(list[a]);

And it works fine.

 var list = [ "john@yahoo.com", "rami@gmail.com", "josh@yahoo.com", "bale@gmail.com" ]; (function() { var obj1 = {}; for (var a = 0, b = list.length; b > a; a++) { var str = list[a].split("@"); var arr = []; arr.push(str[0]); if (!(str[1] in obj1)) { obj1[str[1]] = []; //arr.push(str[0])]; } obj1[str[1]].push(list[a]); }; console.log(obj1); })(); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 

Answer 4

Array.prototype.reduce is typically used to translate array data to object form.

See below for a practical example 👇

 // Emails. const emailAddresses = ["bale@gmail.com", "john@yahoo.com", "rami@gmail.com","josh@yahoo.com"] // Group By Domain. const groupByDomain = addresses => addresses.reduce((acc, email) => { const [prefix, domain] = email.split(/@/) const exists = acc[domain] if (exists) acc[domain].push(email) else acc[domain] = [email] return acc }, {}) // Output. const output = groupByDomain(emailAddresses) // Proof. console.log(output)