How to initialize an empty array of object with a predefined array?

Question

I am facing lot of issue to initialize an array of object with a predefined array. I am not being able to copy that array to my new array of objects. If anyone knows it then let me know.

admins is basically an array which contains string items like ["hello","hii","sup",....]

var admins = ["hello","hii","sup"];
var obj = [];

for(var i=0; i<admins.length; i++)
{
    obj[i].name = admins[i];
}

console.log(obj);

"TypeError: Cannot set property 'name' of undefined"

admins is basically an array which contains string items like ["hello","hii","sup",....] — MOHIT SHARMA
– MOHIT SHARMA, Commented Jun 11, 2019 at 10:53

Umair · Accepted Answer · 2019-06-11 10:51:05Z

6

Use a map:

var newArray = admins.map((admin) => ({ name: admin }));

answered Jun 11, 2019 at 10:51

Umair

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1 Comment

Roy.B Over a year ago

after reviewing the question again, this is the best answer +++1

Mosè Raguzzini · Accepted Answer · 2019-06-11 10:56:32Z

1

IMHO: use spread operator:

const admins = ["John", "Doe", "Duck"];
const obj = [...admins].map(
  (admin) => ({ name: admin })
);
console.log(obj);

edited Jun 11, 2019 at 10:56

answered Jun 11, 2019 at 10:48

Mosè Raguzzini

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8 Comments

Umair Over a year ago

How will this assign name property to each object in the new array?

Mosè Raguzzini Over a year ago

@UmairSarfraz this is not clear if the OP want to set the name. The title says "initialize from predefined array".

MOHIT SHARMA Over a year ago

How will I assign the admins values to the name field of the obj array of object??

Umair Over a year ago

@MosèRaguzzini Thanks for the edit. However, the spread operator is unnecessary in this case as you are already using a map.

Umair Over a year ago

Right, but admins is not an array of objects. It is an array of strings stackoverflow.com/questions/56541905/…

|

Sekar · Accepted Answer · 2019-06-11 10:52:40Z

-1

Try out this

 var obj = [];

for (var i = 0; i < admins.length; i++) {
  let temp = {};
  temp["name"] = admins[i];
  obj.push(temp);
}

console.log(obj);

answered Jun 11, 2019 at 10:52

Sekar

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Comments

Arshpreet Wadehra · Accepted Answer · 2019-06-11 10:47:34Z

-2

You need to define the obj[i] to empty object (obj[i] = {}).

you are trying to access name property of undefined(obj[i] is undefined in your code).

var obj = [];

    for(var i=0; i<admins.length; i++)
    {
     obj[i] = {
      name: admins[i]
     }
   }

    console.log(obj);

answered Jun 11, 2019 at 10:47

Arshpreet Wadehra

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1 Comment

emdibee Over a year ago

This is the only answer that points to the right concept here which the questioner missed. Each element in the array needs to be an object, only then can one define obj[i].something! Don't know why people down-voted this!

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