How to get the object key and value into an array in JS?

Question

I have an object

var students = { 0: "Ann_L", 1: "Bob_P", 2: "Cat_C" }

How can I get an array from the object with its key and value?

var array = [ 
    { "Id": 0, "Value": "Ann_L", "Name": "Ann L" },
    { "Id": 1, "Value": "Bob_P", "Name": "Bob P" },
    { "Id": 2, "Value": "Cat_C", "Name": "Cat C" }
]

I have the values of the object but not the keys for "Id"

var array = Object.entries(students).map(([_, student ]) => 
    ({
        Name: student.replace(/_/g, " "), 
        Id: ?,
        Value: student 
    })

_ contains your key

Lennholm
– Lennholm

2019-04-11 17:24:02 +00:00
Commented Apr 11, 2019 at 17:24 — Lennholm
– Lennholm, Commented Apr 11, 2019 at 17:24

charlietfl · Accepted Answer · 2019-04-11 17:23:43Z

3

The key is the first element in the entries array

var array = Object.entries(students).map(([key, student ]) => 
({
    Name: student.replace(/_/g, " "), 
    Id: key,
    Value: student 
})

answered Apr 11, 2019 at 17:23

charlietfl

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1 Comment

p.s.w.g Over a year ago

Minor note: key will be a string, if Id is supposed to be a number, you probably want Id: +key.

Nina Scholz · Accepted Answer · 2019-04-11 17:27:31Z

2

You could assign the object to an array and map the objects.

var students = { 0: "Ann_L", 1: "Bob_P", 2: "Cat_C" },
    array = Object
        .assign([], students)
        .map((Value, Id) => ({ Id, Value, Name: Value.replace(/_/g, ' ') }));

console.log(array);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Apr 11, 2019 at 17:27

Nina Scholz

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2 Comments

p.s.w.g Over a year ago

Object.assign([], students) is clever.

Scott Sauyet Over a year ago

While the Object.assign call is clever, it's perhaps a bit too clever, as it will only work properly if the keys are 0, 1, 2, etc., albeit in any order. Object.entries(students).map(...) is clearer and less fragile.

Code Maniac · Accepted Answer · 2019-04-11 17:30:42Z

2

Object.entries return [key, value] so in your code _ is key

You can use Object.entries and map and replace

var students = { 0: "Ann_L", 1: "Bob_P", 2: "Cat_C" }

let op = Object.entries(students).map(([Id,value]) => {
  return {
    Id,
    value,
    name: value.replace(/_/g, ' ')
  }
})

console.log(op)

edited Apr 11, 2019 at 17:30

answered Apr 11, 2019 at 17:25

Code Maniac

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Comments

wentjun · Accepted Answer · 2019-04-11 17:27:33Z

1

An alternative solution: you can use Object.keys, and iterate through the students object using the keys.

const students = { 0: "Ann_L", 1: "Bob_P", 2: "Cat_C" }

const res = Object.keys(students).map((element, index) => {
  return {
    Id: element,
    Value: students[index],
    Name: students[index].replace(/_/g, " "),  
  }
})

console.log(res)

answered Apr 11, 2019 at 17:27

wentjun

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