While, I could imagine that there might be some compiler optimizations around a non-subclassed array, what I do not understand at all is how. Remember, the slice method is immutable and the splice method is mutable.In node v14.3.0, I discovered (while doing some coding work with very large arrays) that sub-classing an array can cause. Hopefully this post has helped you understand the difference between JavaScript array's slice and splice methods and how they work. const array = Ĭonsole.log(array) // Conclusion This means that you can set count to 0 with additional parameters to add to the array. Every parameter after the count parameter will be added to the array. You can pass an unlimited number of parameters to the splice method. When you provide both the start and count parameters, it will remove count number of elements, starting at the start index. When you only provide the start parameter, it will remove all elements from that index to the end of the array. The splice method will directly modified the array, essentially adding or removing elements from it using the optional start and count parameters. When you provide both the start and end parameters, it will return the elements between those two indexes. The start parameter can be negative to start at the end of the array. The start parameter is zero-based so the first element is at index 0. If you provide the start parameter, it will start at that index and go until the end of the array. They're both optional so if you leave both blank, it will return the entire array. The slice method will take an array and return a new array with the elements specified by the optional start and end parameters. The difference between slice and splice is that slice is immutable whereas splice will mutate the array.

In this post, we'll learn the difference between the JavaScript array methods slice() and splice() and when it's appropriate to use one over the other.

Array slice in javascript