Javascript For loop iteration count not working

Question

I am trying to push a few objects into an array through a for loop. Although, in that for loop I would like the name of the object to be the current iteration of the for loop. The for loop displayed below runs twice, therefore the Name variable for the first object should be 1 and the name for the second object should be 2. But, in this case for whatever reason, both objects in this array return a Name value of 2. Does anyone know why this would happen?

var ThisArray = [];
var ThisObj = {};

for (var x = 1; x <= 2; x++) {
  ThisObj.Name = x;
  ThisArray.push(ThisObj);
}

console.log(ThisArray);

Use let x=1, instead of var

Rinkesh Golwala
– Rinkesh Golwala

2020-07-21 18:31:27 +00:00
Commented Jul 21, 2020 at 18:31 — Rinkesh Golwala
– Rinkesh Golwala, Commented Jul 21, 2020 at 18:31

Carolyn Hodges · Accepted Answer · 2020-07-21 18:36:50Z

3

You always add the same object. Move the object inside the loop:

const thisArray = [];

for (let x = 1; x <= 2; x++) {
  const thisObj = {};
  thisObj.Name = x;
  thisArray.push(thisObj);
}

console.log(thisArray);

answered Jul 21, 2020 at 18:36

Carolyn Hodges

1816 bronze badges

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

Comments

Alberto · Accepted Answer · 2020-07-21 18:35:12Z

1

You are always pushing the same object in the array, and so the second iteration will edit also the one that was previously inserted; instead, you should do something like this:

var obj= {};
for(let x= 1; x<= 2; x++){
    obj= {};
    obj.name = x;
    arr.push(obj);
}
console.log(arr);

so you will change obj every iteration

PS: better version:

for(let x= 1; x<= 2; x++){
    arr.push({name : 2});
}
console.log(arr);

answered Jul 21, 2020 at 18:35

Alberto

13.1k3 gold badges31 silver badges72 bronze badges

1 Comment

Sid Nutthi Over a year ago

Thank you so much! I would upvote it, but I don't have enough points yet.

gmiley · Accepted Answer · 2020-07-21 18:34:25Z

1

You are simply reassigning the value of the Name property of the ThisObj to a new value. It is a reference, so you need to create a new instance each time you want to add a new item. Move the variable declaration into the for loop:

var ThisArray= [];
    for(var x= 1; x<= 2; x++){
      var ThisObj= {};
      ThisObj.Name = x;
     
      ThisArray.push(ThisObj);
    }
console.log(ThisArray);

answered Jul 21, 2020 at 18:34

gmiley

6,6041 gold badge15 silver badges25 bronze badges

1 Comment

Sid Nutthi Over a year ago

Thank you so much! I would upvote this as well, but I don't have enough points yet.

Cody Gray · Accepted Answer · 2020-07-22 05:25:42Z

0

Your problem is that you push twice the same object.

Here is what you want:

var ThisArray = [];
for (var x = 1; x <= 2; x++) {
    var ThisObj = {};
    ThisObj.Name = x;

    ThisArray.push(ThisObj);
}
console.log(ThisArray);

edited Jul 22, 2020 at 5:25

Cody Gray♦

246k53 gold badges512 silver badges591 bronze badges

answered Jul 21, 2020 at 18:48

8HoLoN

1,1607 silver badges15 bronze badges

Collectives™ on Stack Overflow

Javascript For loop iteration count not working

4 Answers 4

Comments

1 Comment

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related