modify array of objects by reduce

Question

I have an array like ->

[{amount: 5000, date: "2020-04", user: "Bill Gates"}, {amount: 5000, date: "2020-04", user: "Jon Jones"}, {amount: 5000, date: "2020-05", user: "Jon Jones"}, {amount: 5000, date: "2020-05", user: "Bill Gates"}, ...]

And I want to modify it to ->

[{user: "Bill Gates", data: [{amount: 5000, date: "2020-04"}, {amount: 5000, date: "2020-05"}]}, {user: "Jon Jones", data: [{amount: 5000, date: "2020-04"}, {amount: 5000, date: "2020-05"}]}, ....]

I write reduce function ->

let reduced = array.reduce((sells, {user, date, amount}) => ({
    ...sells,
    user: user,
    data: [{date: date, amount: amount}],
}),{});

but it returns just one item of array. How can I return all of them?

Amardeep Bhowmick · Accepted Answer · 2020-05-03 19:49:43Z

2

You can search for the user using Array.prototype.find if found that means it is already processed and you can push the data object in the existing array else create a new object and insert it in the accumulator:

const data = [{amount: 5000, date: "2020-04", user: "Bill Gates"}, {amount: 5000, date: "2020-04", user: "Jon Jones"}, {amount: 5000, date: "2020-05", user: "Jon Jones"}, {amount: 5000, date: "2020-05", user: "Bill Gates"}];

const result = data.reduce((sells, {user, date, amount}) => {
   let match = sells.find(e => e.user === user);
   if(match){
      match.data.push({amount, date});
   }else{
      match = {user, data : [{amount, date}]};
      sells.push(match);
   }
   return sells;
}, []);
console.log(result);

edited May 3, 2020 at 19:49

answered May 3, 2020 at 19:47

Amardeep Bhowmick

17k3 gold badges33 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

grzim · Accepted Answer · 2020-05-03 19:54:59Z

1

input.reduce((acc, {user, amount, date}) => {
    const userToExtend = acc.find(u => u.user === user)
    if(userToExtend) userToExtend.data.push[{amount, date}]
    else acc.push({user, data: [{amount, date}]});
    return acc
}, []);

answered May 3, 2020 at 19:54

grzim

6044 silver badges10 bronze badges

Collectives™ on Stack Overflow

modify array of objects by reduce

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related