JavaScript Array splice vs slice

Question

splice() changes the original array whereas slice() doesn't but both of them returns array object.

See the examples below:

var array=[1,2,3,4,5];
console.log(array.splice(2));

This will return [3,4,5]. The original array is affected resulting in array being [1,2].

var array=[1,2,3,4,5]
console.log(array.slice(2));

This will return [3,4,5]. The original array is NOT affected with resulting in array being [1,2,3,4,5].

Below is simple fiddle which confirms this:

//splice
var array=[1,2,3,4,5];
console.log(array.splice(2));

//slice
var array2=[1,2,3,4,5]
console.log(array2.slice(2));


console.log("----after-----");
console.log(array);
console.log(array2);

Splice and Slice both are Javascript Array functions.

Splice vs Slice

1. The splice() method returns the removed item(s) in an array and slice() method returns the selected element(s) in an array, as a new array object.

2. The splice() method changes the original array and slice() method doesn’t change the original array.

3. The splice() method can take n number of arguments and slice() method takes 2 arguments.

Splice with Example

Argument 1: Index, Required. An integer that specifies at what position to add /remove items, Use negative values to specify the position from the end of the array.

Argument 2: Optional. The number of items to be removed. If set to 0(zero), no items will be removed. And if not passed, all item(s) from provided index will be removed.

Argument 3…n: Optional. The new item(s) to be added to the array.

var array=[1,2,3,4,5];
console.log(array.splice(2));
// shows [3, 4, 5], returned removed item(s) as a new array object.
 
console.log(array);
// shows [1, 2], original array altered.
 
var array2=[6,7,8,9,0];
console.log(array2.splice(2,1));
// shows [8]
 
console.log(array2.splice(2,0));
//shows [] , as no item(s) removed.
 
console.log(array2);
// shows [6,7,9,0]

Slice with Example

Argument 1: Required. An integer that specifies where to start the selection (The first element has an index of 0). Use negative numbers to select from the end of an array.

Argument 2: Optional. An integer that specifies where to end the selection but does not include. If omitted, all elements from the start position and to the end of the array will be selected. Use negative numbers to select from the end of an array.

var array=[1,2,3,4,5]
console.log(array.slice(2));
// shows [3, 4, 5], returned selected element(s).
 
console.log(array.slice(-2));
// shows [4, 5], returned selected element(s).
console.log(array);
// shows [1, 2, 3, 4, 5], original array remains intact.
 
var array2=[6,7,8,9,0];
console.log(array2.slice(2,4));
// shows [8, 9]
 
console.log(array2.slice(-2,4));
// shows [9]
 
console.log(array2.slice(-3,-1));
// shows [8, 9]
 
console.log(array2);
// shows [6, 7, 8, 9, 0]

S LICE = Gives part of array & NO splitting original array

SP LICE = Gives part of array & SPlitting original array

I personally found this easier to remember, as these 2 terms always confused me as beginner to web development.

Here is a simple trick to remember the difference between slice vs splice

var a=['j','u','r','g','e','n'];

// array.slice(startIndex, endIndex)
a.slice(2,3);
// => ["r"]

//array.splice(startIndex, deleteCount)
a.splice(2,3);
// => ["r","g","e"]

Trick to remember:

Think of "spl" (first 3 letters of splice) as short for "specifiy length", that the second argument should be a length not an index