8.3.1. Common Array Methods // splice Examples (.splice)
//The general syntax for this method is:
arrayName.splice(index, number of elements to change, item1, item2, ...);
//Inside the parentheses (), only the first argument is required.
/*The splice method modifies one or more elements anywhere in the array.
Entries can be added, removed, or changed. This method requires
practice.*/
/*To remove elements from an array, the splice method needs 1 or 2
arguments.
Given only one argument, splice(index) removes every entry from index
to the end of the array.*/
let arr = ['a', 'b', 'c', 'd', 'e', 'f'];
arr.splice(2); //Everything from index 2 and beyond is removed.
console.log(arr);
//['a', 'b']
/*With two arguments, splice(index, number of items) starts at index
and removes the specified number of items from the array.*/
let arr = ['a', 'b', 'c', 'd', 'e', 'f'];
arr.splice(2,3); //Start at index 2 and remove 3 total entries.
console.log(arr);
arr.splice(1,1); //Start at index 1 and remove 1 entry.
console.log(arr);
//[ 'a', 'b', 'f' ]
//[ 'a', 'f' ]
/*To add or replace elements in an array, the splice method requires
3 or more arguments.
To add elements, set the number of elements argument to 0 and follow
this with the new items.*/
//Example:
/*splice(index, 0, new item) starts at index and INSERTS the new items.
Existing elements get shifted further down the array.*/
let arr = ['a', 'b', 'c', 'd', 'e', 'f'];
arr.splice(2,0,'hello'); //Start at index 2, remove 0 entries, and add 'hello'.
console.log(arr);
//[ 'a', 'b', 'hello', 'c', 'd', 'e', 'f' ]
/*To replace elements in an array, the number of elements argument
must be a positive integer. Follow this with the new items for the
array.*/
//Example:
/*splice(index, number of items, new items) starts at index and
REPLACES the number of items with the new ones.*/
let arr = ['a', 'b', 'c', 'd', 'e', 'f'];
arr.splice(2,3,'hello', 9); //Start at index 2, replace 3 entries with 'hello' and 9.
console.log(arr);
//[ 'a', 'b', 'hello', 9, 'f' ]