JavaScript Clone Array Example

JavaScript provides several methods to copy, clone, or duplicate arrays and objects. This tutorial will show you simplest, different and easiest way to copy, clone or duplicate an array and objects in javaScript.

There are at least 6 (!) ways to clone an array and objects in JavaScript

• 1: Spread Operator(fastest) Way to Clone array
• 2: Slice Operator Clone array
• 3: Concat Clone array
• 4: Clone array using From() method
• 5: Clone Array Using For loop
• 6: Deep Copy Array

1: Spread Operator(fastest) Way to Clone array

var arr = [1,2,3,4,5];

// Spread Operator  
var arr1 = [...arr];

2: Slice Operator Clone array

var arr = [1,2,3,4,5];

// Slice Operator
var arr2 = arr.slice();

3: Concat Clone array

var arr = [1,2,3,4,5];

// Concat
var arr3 = [].concat(arr)

4: Clone array using From() method

var arr = [1,2,3,4,5];

// Array.from()
var arr4 = Array.from(arr);

5: Clone Array Using For loop

// For loop
function arr5(arr) {
  let newArr = [];
  for(let i=0; i<arr.length; ++i) {
      newArr[i] = arr[i];
  }
  return arr;
}

Note: All of the above are shallow copies. If the original array is multi-dimensional there will be problems since you need a deep copy.

6: Deep Copy Array

You can solve this by serializing the entire array to JSON and then de-serializing it, but this results in bad performance and doesn’t work with special objects.

// Deep copy
const dupArray = JSON.parse(JSON.stringify(arr))

How to Copy Objects in JavaScript?

Answer: Using the javascript methods to Clone(Copy) Objects with examples

Fast cloning with data loss – JSON.parse/stringify

var obj = {
  name: 'string',
  number: 123,
  email : '[email protected]'
  bool: false,
  nul: null,
  date: new Date(),  // stringified
}
console.log(obj);
console.log(typeof obj.date); 

var clone = JSON.parse(JSON.stringify(obj));
console.log(clone);

Using the assign() method to clone the object

Object.assign () or Spread syntax can be used for a copy but it will be the shallow copy.

var orgObj= {
  name: 'Dell',
  laptop: {
    color: 'black'
  }
}
var copiedObj = Object.assign({}, orgObj)

orgObj.name = 'Dell I5'
orgObj.car.color = 'BLUE'

copiedObj.name //Dell
copiedObj.laptop.color //black

Conclusion

In this clone, copy or duplicate arrays and objects tutorial, you have learned how to clone, copy or duplicate javascript arrays and objects using the simplest methods.

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