How to clone an array by value in JavaScript?

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1

I want to duplicate an array in JavaScript so that each has its own copy. Here’s my code:

let originalArray = ['x', 'y', 'z'];
let newArray = originalArray;
newArray.push('w');  // Both originalArray and newArray are ['x', 'y', 'z', 'w']

I learned that newArray shares the same reference as originalArray. How can I create separate arrays that don’t affect each other?

2

Hey there! :blush: It looks like you want to create a true copy of an array so that changes don’t affect the original. In JavaScript, you can achieve this using the spread operator or the slice() method. Here’s how you can do it:

// Using the spread operator
let originalArray = ['x', 'y', 'z'];
let newArray = [...originalArray];
newArray.push('w');  // newArray is ['x', 'y', 'z', 'w'], originalArray is still ['x', 'y', 'z']

// Using slice()
let anotherArray = originalArray.slice();
anotherArray.push('a');  // anotherArray is ['x', 'y', 'z', 'a'], originalArray remains unchanged

Both these methods make a shallow copy of your array. It’s a neat trick when you want to keep your original data unaltered! Let me know if you need more examples or have any questions. :balloon:

3

Creating separate copies of an array in JavaScript can be essential to prevent unintended changes between them. Here’s a clear way to accomplish this:

let originalArray = ['x', 'y', 'z'];

// Create a copy using Array.from()
let newArrayFrom = Array.from(originalArray);
newArrayFrom.push('w');
// newArrayFrom is ['x', 'y', 'z', 'w'], originalArray remains ['x', 'y', 'z']

// Or use the concat() method for a similar outcome
let concatArray = originalArray.concat();
concatArray.push('a');
// concatArray is ['x', 'y', 'z', 'a'], while originalArray stays as ['x', 'y', 'z']

Explanation:

  • Array.from(): This method is useful for creating a new array instance from the original array, ensuring they no longer share the same reference.
  • concat(): This method can also be used to create a shallow copy, assisting in keeping your original array unchanged.

These simple techniques allow you to safely duplicate arrays without impacting the original. If you have further questions or need more demonstrations, feel free to ask!

4

Greetings,

For independent array copies in JavaScript, try map():

let originalArray = ['x', 'y', 'z'];
let newArray = originalArray.map(item => item);
newArray.push('w');  // newArray is ['x', 'y', 'z', 'w'], originalArray remains ['x', 'y', 'z']

This creates a new array without affecting the original.