The array data structure is one of the most commonly used data structures in programming. It is used to store collections of data, such as a list of names or a collection of objects. In JavaScript, arrays are an object type and have a variety of methods available to them. Some of these methods modify the array they are called on, while others do not. This article will explain the differences between mutating and non-mutating array methods in JavaScript.

Mutating methods are those that modify the array they are called on. If you call a mutating array method, the array will be changed. Examples of mutating array methods include push(), pop(), shift(), unshift(), and splice(). These methods add or remove elements from the array, or modify existing elements.

Non-mutating methods are those that don’t modify the array they are called on. If you call a non-mutating array method, the original array will remain unchanged. Examples of non-mutating array methods include map(), filter(), and reduce(). These methods create a new array from the elements of the original array, but do not modify the original array.

It’s important to understand the difference between mutating and non-mutating array methods, as this will affect how you use them in your code. If you’re writing code that needs to keep track of the original array, you should use non-mutating methods. On the other hand, if you’re writing code that needs to modify the array in-place, you should use mutating methods.

In addition to the differences between mutating and non-mutating array methods, there are also differences in the performance of these methods. Mutating methods tend to be faster than non-mutating methods, as they don’t need to create a new array. However, this performance gain comes at the cost of code readability and maintainability, as mutating methods can be more difficult to understand and debug.

Overall, understanding the differences between mutating and non-mutating array methods in JavaScript is essential for writing efficient and maintainable code. Mutating methods are faster than non-mutating methods, but require more caution when used. Non-mutating methods are slower, but can be easier to understand and debug.