Javascript Array concat() is an inbuilt method that is used to merge the two or more arrays. The concat() function does not modify the existing array but instead returns the new array. The concat() method does not alter this or any of the arrays provided as arguments but instead returns a shallow copy that contains copies of the same elements combined from the original arrays.

Javascript Array Concat Example

Javascript array concat() method does not change the existing  arrays but returns a new array containing the values of the joined arrays. It is the sign of immutability of objects because you can not merely change anything inside an array.

It counts as a  pure function, and pure function always returns a new copy of the existing  array of objects. If you have used  Redux previously, then you have known that we used this concat function to return a new state of the class and not modify that state of the class.

#javascript #js array concat