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Copy an Array in JavaScript – onlinecode

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Copy an Array in JavaScript - onlinecode

Copy an Array in JavaScript

In this post, we will give you information about Copy an Array in JavaScript. Here we will give you detail about Copy an Array in JavaScript And how to use it also give you a demo for it if it is necessary.

There are several easy ways to clone an array in JavaScript. You can use the Array#slice() method, or the spread operator.

const arr = ['hello', 'world'];

// Clone using 'slice()'
const arr2 = arr.slice();
arr2; // ['hello', 'world']
arr2 === arr; // false

// Clone using spread operator '...'
const arr3 = [...arr];
arr2; // ['hello', 'world']
arr2 === arr; // false

Two other common approaches are by concat()-ing the array to an empty array and by using the map() method:

// Clone using 'concat()'
const arr4 = [].concat(arr);
arr4; // ['hello', 'world']
arr4 === arr; // false

// Clone using 'map()'
const arr5 = arr.map(v => v);
arr5; // ['hello', 'world']
arr5 === arr; // false

These 4 approaches for copying an array are effectively identical and there isn’t much reason to prefer one over
the other. The most significant difference is that slice() enjoys slightly better browser support – all the
way back to Internet Explorer 4.

Deep Copy vs Shallow Copy for Copy an Array in JavaScript

Keep in mind that all 4 of the above approaches create a shallow clone of the
array. In other words, they clone the array itself, but not the array elements.

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This difference doesn’t matter when you have an array of primitives (numbers, strings, null, undefined), but
it does when you have an array of objects.

const arr = [{ answer: 42 }];

const arr2 = arr.slice();
arr2[0].answer = 0;

// '0', because 'arr[0]' is a reference to the same object as 'arr2[0]'
arr[0].answer;

JavaScript doesn’t have a built-in approach for deep cloning an array. You would need to use a library that
has a cloneDeep() function, like lodash.

const arr = [{ answer: 42 }];

const arr2 = require('lodash').cloneDeep(arr);
arr2[0].answer = 0;

// '42', because Lodash did a deep clone.
arr[0].answer;

JavaScript Fundamentals for Copy an Array in JavaScript

JavaScript is a programming language that is used to create interactive web pages. It is a client-side scripting language, which means that it runs on the user’s browser. JavaScript can be used to add animation, interactivity, and functionality to web pages.

Here are some of the fundamentals of JavaScript:

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These are just some of the fundamentals of JavaScript. There are many other concepts that you can learn as you continue to develop your skills.

Here are some resources that you can use to learn more about JavaScript:

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I hope this helps!

Here are some additional tips for learning JavaScript:

With a little practice, you’ll be able to learn JavaScript and start building amazing web applications.

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