Create new JSON array from given JSON array in JavaScript

Question

For example I have an array like this

{
  "employees": [
    { "name": "Ram", "email": "[email protected]", "age": 23 },
    { "name": "Shyam", "email": "[email protected]", "age": 28 },
    { "name": "John", "email": "[email protected]", "age": 33 },
    { "name": "Bob", "email": "[email protected]", "age": 41 }
  ]
}

If I want an array like {"sam","shyan","john","bob"} I got it , just using map

arrayname.map((item) => item.name);

BUT if I want an array like this from above array

{
  "employees": [
    { "name": "Ram", "email": "[email protected]" },
    { "name": "Shyam", "email": "[email protected]" },
    { "name": "John", "email": "[email protected]" },
    { "name": "Bob", "email": "[email protected]" }
  ]
}

How can I do that? Thank you a lots

CertainPerformance · Accepted Answer · 2021-08-26 03:26:41Z

3

For the general situation where you want to remove one property from all objects in an array, you can destructure that property and collect the rest with rest syntax.

const employees = [    
    {"name":"Ram", "email":"[email protected]", "age":23},    
    {"name":"Shyam", "email":"[email protected]", "age":28},  
    {"name":"John", "email":"[email protected]", "age":33},    
    {"name":"Bob", "email":"[email protected]", "age":41}   
];

const result = employees.map(({ age, ...rest }) => rest);
console.log(result);

If you want to keep a number of them, then destructure those and list them in the returned object.

const employees = [    
    {"name":"Ram", "email":"[email protected]", "age":23},    
    {"name":"Shyam", "email":"[email protected]", "age":28},  
    {"name":"John", "email":"[email protected]", "age":33},    
    {"name":"Bob", "email":"[email protected]", "age":41}   
];

const result = employees.map(({ name, email }) => ({ name, email }));
console.log(result);

edited Aug 26, 2021 at 3:26

answered Aug 26, 2021 at 3:16

CertainPerformance

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2 Comments

Lê Quốc Khánh Over a year ago

No , that was an example, i have tons of item, then if i want to keep 2 of them, how can i do that?, but thank you btw bro

Guilherme A C Zaluchi Over a year ago

Genial solution. I c'dn't think of a powerful (yet simple) solution as yours.

Guilherme A C Zaluchi · Accepted Answer · 2021-08-26 03:21:52Z

1

As you said:

array.employees.map(function(item, _i, _array){
  return item.name;
});

Would get you an array in the form:

[
  "sam", "shyan", "john", "bob"
]
// But not {"sam", "shyan", "john", "bob"}. These are other things.

As the type of item you want is in the form:

{ name: "Ram", email: "[email protected]" }

You want your function to return an object for each item it receives. There are (maybe really) thousands of ways to do so. Let's try something simple:

function(item, _i, _array){
  // returning an object
  return {
    // the 'name' property takes the value from the item
    name: item.name,
    // same for the 'email'
    email: item.email
  };
}

answered Aug 26, 2021 at 3:21

Guilherme A C Zaluchi

694 bronze badges

3 Comments

Lê Quốc Khánh Over a year ago

Btw how can i get {"sam", "shyan", "john", "bob"}? I notice that when i create an array using map it alway wrap with another object, now i understand

Guilherme A C Zaluchi Over a year ago

@LêQuốcKhánh An array created with Array.prototype.map (link to the MDN, the best place for the documentation) will be an, er... an Array. And Arrays are JS objects.

Guilherme A C Zaluchi Over a year ago

@LêQuốcKhánh What I said about the {"sam", "john", "bob"} thing is actually { sam, john, bob }, which is related to the Destructuring Assignment.

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