8. What are the differences between slice and splice functions?

slice can be invoked on an array and it accepts 2 arguments - startIndex i endIndex. It returns copy of an original array consisting of elements starting from startIndex and ending on endIndex (excluding endIndex element).

If endIndex was not passed, returned list will contain all elements from startIndex to an end.

Negative indexes will cause counting from the end

slice doesn't modify original list - it returns copy!

const list = ["a", "b", "c"];
console.info(list.slice(0, 2)); // ["a", "b"]
console.info(list.slice(1)); // ["b", "c"]
console.info(list.slice(4)); // []
console.info(list.slice(0, -1)); // ["a", "b"]
console.info(list.slice(-2)); // ["b", "c"]
console.info(list); // ["a", "b", "c"]

splice can be invoked on an array and it accepts arguments startIndex, deleteCount and ...additionalElements.

deleteCount items will be removed from original list starting from startIndex.

If deleteCount wasn't passed, all elements from startIndex to the end will be removed

Every next argument is a value which will be added in place of removed items

Negative startIndex value will cause counting from the end

splice modifies original array!

const list1 = ["a", "b", "c"];
const list2 = ["a", "b", "c"];
const list3 = ["a", "b", "c"];
console.info(list1.splice(0, 2)); // ["a", "b"]
console.info(list1); // ["c"]
console.info(list2.splice(1, 1, "d")); // ["b"]
console.info(list2); // ["a", "d", "c"]
console.info(list3.splice(-3, 1, "d")); // ["b"]
console.info(list3); // ["d", "b", "c"]