splice Examples

.splice() Examples

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.

Hang on, here we go:

Removing Elements

To remove elements from an array, the splice method needs 1 or 2 arguments.

1. Given only one argument, splice(index) removes every entry from index to the end of the array.

   Example

   let arr = ['a', 'b', 'c', 'd', 'e', 'f'];
   
   arr.splice(2);    //Everything from index 2 and beyond is removed.
   console.log(arr);

   Output

   ['a', 'b']
   

2. With two arguments, splice(index, number of items) starts at index and removes the specified number of items from the array.

   Example

   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);

   Output

   [ 'a', 'b', 'f' ]
   [ 'a', 'f' ]
   

Adding or Replacing Elements

To add or replace elements in an array, the splice method requires 3 or more arguments.

1. 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);

   Output

   [ 'a', 'b', 'hello', 'c', 'd', 'e', 'f' ]
   

2. 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);

   Output

   [ 'a', 'b', 'hello', 9, 'f' ]