JavaScript Array length (original) (raw)

Last Updated : 16 Nov, 2024

**JavaScript array length property is used to set or return the number of elements in an array.

JavaScript `

let a = ["js", "html", "gfg"];

console.log(a.length);

`

Setting the Length of an Array

The length property can also be used to set the length of an array. It allows you to truncate or extend the array.

**Truncating the Array

JavaScript `

let a = ["js", "html", "gfg"]; a.length = 2;

console.log(a);

`

**Extending an Array

JavaScript `

let a = ["js", "html", "gfg"]; a.length = 5;

console.log(a);

`

Output

[ 'js', 'html', 'gfg', <2 empty items> ]

size() vs length for finding length

Underscore.js defines a size method which actually returns the length of an object or array, but size is not a native method. So it is always recommended to use length property.

String Length vs Array Length Property

String Length properly works same way, but we cannot modify length of a string as strings are immutable.

JavaScript `

let a = ["js", "css", "html"]; a.length = 2; // Changes length of array console.log(a);

let s = "geeksforgeeks" s.length = 3; // Has no effect on string console.log(s);

`

Output

[ 'js', 'css' ] geeksforgeeks