Docly Developers
Function Updated 17 Oct 2026

Array.splice(start, [deleteCount], [item1...N])

Changes the contents of an array by removing or replacing existing elements and/or adding new elements at specified index.

Parameters

startintrequired

Index where items are removed and inserted. A negative value counts from the end of the array.

deleteCountintoptional

Number of items to remove. If omitted, every item from start to the end is removed.

item1...Nobjectoptional

Items to insert at start (zero or more).

Returns

An array of the items that were removed. The array itself is changed.

Example

Normal JavaScript, running in the browser or on the Docly™ server.
const months = ['Jan', 'March', 'April', 'June'];
months.splice(1, 0, 'Feb');
/* Inserts at index 1 */
write(JSON.stringify(months));
/* Expected output: ["Jan","Feb","March","April","June"] */

write("\n");
months.splice(4, 1, 'May');
/* Replaces 1 element at index 4 */
write(JSON.stringify(months));
/* Expected output: ["Jan","Feb","March","April","May"] */