How to clone an item of objects in array?

Question

I have an array as given below -

var x = [{
    name: "Mr.X", 
    age: 22
},{
    name: "Mr.Y", 
    age: 26
},{
    name: "Mr.Z", 
    age: 24
},];

I want to duplicate the 2nd item and put it as the first element. Just to avoid any confusion, I want the resultant array to be as given below -

var x = [{
    name: "Mr.YD", 
    age: 19
},{
    name: "Mr.X", 
    age: 22
},{
    name: "Mr.Y", 
    age: 26
},{
    name: "Mr.Z", 
    age: 24
},];

What I have tried and got - I extracted the 2nd item, and changed the name and age properties. But it is also changing the 2nd item. I know it is because we are changing the reference. But i have no idea how to extract/duplicate item and change only its value.

Is there a specific reason you need to clone an existing object in the array instead of just creating a new one? — Rory McCrossan
– Rory McCrossan, Commented Nov 30, 2015 at 11:23
I didn't follow your question. But the resultant array could be "y" instead of "x". — anand patil
– anand patil, Commented Nov 30, 2015 at 11:24
@RayonDabre - Only one thing - the result should also be an array of objects, just like the input. — anand patil
– anand patil, Commented Nov 30, 2015 at 11:31
JSON.stringify is being used just to demonstrate the result..You can remove it! — Rayon
– Rayon, Commented Nov 30, 2015 at 11:32

Bijeshp009 · Accepted Answer · 2015-11-30 11:56:25Z

1

if you are looking for clone of the object there are multiple ways

jQuery Extend:

// Shallow copy
  var newObject = jQuery.extend({}, oldObject);

  // Deep copy
  var newObject = jQuery.extend(true, {}, oldObject);

JSON Stringify

var newObject =  JSON.parse(JSON.stringify(oldObject))

Or : Write a clone method by iterating through object props recursively

Then append to the array using the standard array APIs

answered Nov 30, 2015 at 11:56

Bijeshp009

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Comments

Fraz Ghumman · Accepted Answer · 2015-11-30 12:12:32Z

1

var x = [{
    name: "Mr.X", 
    age: 22
},{
    name: "Mr.Y", 
    age: 26
},{
    name: "Mr.Z", 
    age: 24
},];
console.log(x);
var y = JSON.parse(JSON.stringify(x));
y.unshift({
    name: "Mr.XD", 
    age: 19
});
console.log(y);

Unshift appends on top of array
Push appends on the end of array

edited Nov 30, 2015 at 12:12

answered Nov 30, 2015 at 11:55

Fraz Ghumman

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1 Comment

Alnitak Over a year ago

while it usually works, I would never recommend using JSON just to clone an object.

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