How to nest element of an object inside the same object in javascript?

Question

I created a form to get some info from User, and I want to move some of their info into a nested object. the reason why is to better organize my data later in front-end.

As a simple example, how to create the following "newInfo" out of "oldInfo" in JavaScript?

oldInfo = {
  name: 'John',
  Age: '32',
  friend1: 'Michael',
  friend2: 'Peter',
};

newInfo = {
  name: 'John',
  Age: '32',
  friends: {
    friend1: 'Michael',
    friend2: 'peter',
  },
};

I'm sure this must be a repeated and simple topic, but I couldn't find any as I didn't know what keyword to search for.

hgb123 · Accepted Answer · 2020-08-02 02:33:57Z

2

You could explicitly assign it

const oldInfo = {
  name: "John",
  Age: "32",
  friend1: "Michael",
  friend2: "Peter",
}

const newInfo = {
  name: oldInfo.name,
  Age: oldInfo.Age,
  friends: {
    friend1: oldInfo.friend1,
    friend2: oldInfo.friend2,
  },
}

console.log(newInfo)

answered Aug 2, 2020 at 2:33

hgb123

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1 Comment

Babak Over a year ago

Thanks, works fine, but since the number of fields in friend:name are dynamic (the example above was simplified to better show my problem) I need to use a code rather than assigning them explicitly

andsilver · Accepted Answer · 2020-08-02 02:36:16Z

2

You can do this easily with spread operator:

const { name, Age, ...friends } = oldInfo;
newInfo = { name, Age, friends };

It simply extracts all fields except name and age as friends.

Example:

const oldInfo = {
  name: 'John',
  Age: '32',
  friend1: 'Michael',
  friend2: 'Peter',
};
const { name, Age, ...friends } = oldInfo;
const newInfo = { name, Age, friends };
console.log(newInfo);

edited Aug 2, 2020 at 2:36

answered Aug 2, 2020 at 2:26

andsilver

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Comments

Ramesh Reddy · Accepted Answer · 2020-08-02 02:43:48Z

0

If you have a dynamic number of friend: name key-value pairs and other properties that shouldn't be nested into friends then you can use Object.entries and reduce:

const oldInfo = {
  name: 'John',
  Age: '32',
  friend1: 'Michael',
  friend2: 'Peter',
};

const newInfo = Object.entries(oldInfo).reduce((acc, [k, v]) => {
  if(k.startsWith('friend')) {
    acc.friends ? acc.friends[k] = v : acc.friends = {[k]: v};
  } else {
    acc[k] = v;
  }
  return acc;
},{});

console.log(newInfo);

edited Aug 2, 2020 at 2:43

answered Aug 2, 2020 at 2:34

Ramesh Reddy

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2 Comments

Babak Over a year ago

Thanks Ramesh, creative code, the only problem is that in my example I wrote above all keys start with friend (friend1, friend2...) yet in my actual problem there are other keys which are not alphabetically similar. This method though is very useful and I definitely use it in my other problems

Ramesh Reddy Over a year ago

@Babak Happy to help. You can update your question with the actual object if you want an answer for that.

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