JavaScript Internals (521 Qs)•Part 1: Core Objects, Prototypes, Functions & Scope (1 - 53)
What is the difference between slice and splice
Here are the key differences between slice() and splice() methods in JavaScript arrays:
slice() | splice() |
|---|---|
| Does not modify the original array (immutable) | Modifies the original array (mutable) |
| Returns a shallow copy (subset) of selected elements | Returns an array of the removed elements |
| Used to extract elements from an array | Used to add, remove, or replace elements in an array |
Syntax: array.slice(start, end) | Syntax: array.splice(start, deleteCount, ...items) |
Summary:
- Use
slice()when you want to copy or extract elements without altering the original array. - Use
splice()when you need to add, remove, or replace elements and want to change the original array.
Practical Code Example
javascript
// slice(): Non-mutating (returns shallow copy of portion)
const original = ['a', 'b', 'c', 'd', 'e'];
const sliced = original.slice(1, 4);
console.log(sliced); // ['b', 'c', 'd']
console.log(original); // ['a', 'b', 'c', 'd', 'e'] (unchanged)
// splice(): Mutating (adds/removes elements in place)
const fruits = ['apple', 'banana', 'cherry', 'date'];
const removed = fruits.splice(1, 2, 'blueberry', 'mango');
console.log(removed); // ['banana', 'cherry']
console.log(fruits); // ['apple', 'blueberry', 'mango', 'date'] (mutated!)