Another term to understand is deep copy, which, unlike the previously mentioned shallow copy, does create a separate memory location and therefore an update to the original assignment will not update the reference. That means that since we are working with a reference, updating the values in the original assignment will also update the reference. Shallow copy is when we copy a reference variable to a new variable using the variable assignment operator ( =). Also note that slice() will not modify the original array: Please note that the index specified at end is not included in the new array. With slice() we can return a so called shallow copy of an array based on the start and end parameters, which are essentially index locations. The signature specifies two optional parameters: slice (start, end ) Let's start with the slice() method first. Their functionality is very similar, however there are some critical differences between the two. Personally, I always mix-up two array methods in particular: slice and splice. We can iterate through arrays, push elements, pop values (remove and return the last element) and slice and dice the array as we see fit. Increment the index after performing the splice.Working with arrays in JavaScript is a fairly common task and the language provides us developers with a myriad of methods. For each item in the first array splice it into the copied array in the index given as argument. Loop through all of the items in the first array. This can be done by using the slice operation on the second array, and assign it to a variable.

This will ensure that the original array is not mutated. Relevant LinksĬreate a copy of the second array inside of the function. That is, we cannot make any changes to the original arrays.

We’ve also got to ensure that the original arrays are not mutated. We need to copy each element from the first array into the second array starting at the index n.

Array js slice