JavaScript Array sort() Method

The Array.sort() method is a built-in JavaScript function used to sort the elements of an array in place. It organizes the elements either in ascending or descending order based on a specified compare function.

By default, the sort() method converts elements to strings and sorts them lexicographically, which can lead to unexpected results when sorting numbers.

Syntax

arr.sort(compareFunction);

Parameters

Parameter	Description
compareFunction	(Optional) A function that defines the sort order. If omitted, elements are converted to strings and sorted lexicographically.

Return Value

The sort() method returns the sorted array. The original array is modified.

Example 1: Default Lexicographic Sorting

let arr = ['banana', 'apple', 'mango', 'cherry'];

arr.sort();
console.log(arr); 
// Output: ['apple', 'banana', 'cherry', 'mango']

By default, sort() method arrange elements in lexicographic (dictionary) order.

Example 2: Sorting Numbers Without a Compare Function

let arr = [10, 101, 1, 25, 3];

arr.sort();
console.log(arr); 
// Output: [1, 10, 101, 25, 3]

Without a compare function, numbers are treated as strings and sorted lexicographically, resulting in incorrect numerical order.

Example 3: Sorting Numbers with a Compare Function

let arr = [10, 101, 1, 25, 3];

arr.sort((a, b) => a - b);
console.log(arr); 
// Output: [ 1, 3, 10, 25, 101 ]

Here, the compare function a - b ensures correct numerical sorting in ascending order.

Example 4: Descending Order Sorting

let arr = [10, 101, 1, 25, 3];
arr.sort((a, b) => b - a);
console.log(arr); 
// Output: [101, 25, 10, 3, 1]

By reversing the order in the compare function (b - a), the array is sorted in descending order.

Example 5: Sorting an Array of Strings with Case Sensitivity

let arr = ['banana', 'apple', 'Apple', 'cherry'];
arr.sort();
console.log(arr); 
// Output: [ 'Apple', 'apple', 'banana', 'cherry' ]

By default, sort() is case-sensitive and places uppercase letters before lowercase ones due to Unicode values.

Example 6: Sorting an Array of Objects

let users = [
  { name: 'John', age: 25 },
  { name: 'Alice', age: 30 },
  { name: 'Bob', age: 20 }
];

users.sort((a, b) => a.age - b.age);
console.log(users);
/* Output: [
    { name: 'Bob', age: 20 },
    { name: 'John', age: 25 },
    { name: 'Alice', age: 30 }
]  */

Supported Browsers

Browser	Support
Chrome	1+
Firefox	1+
Safari	1+
Edge	12+
Opera	4+
Internet Explorer	5.5+