How to Sort an Array in JavaScript

Sorting arrays is a common operation in JavaScript programming. JavaScript provides built-in methods to sort arrays in various ways, allowing you to organize data in ascending or descending order. This article will explore different methods to sort arrays, including numerical and alphabetical sorting, as well as custom sorting functions.

Sorting Arrays with `sort()`

The sort() method sorts the elements of an array in place and returns the sorted array. By default, it sorts the elements as strings in ascending order.


// Default sorting (ascending order)
const numbers = [5, 2, 9, 1, 5, 6];
numbers.sort();
console.log(numbers); // Output: [1, 2, 5, 5, 6, 9]

In this example:

The sort() method converts the numbers to strings and sorts them lexicographically.

Sorting Arrays Numerically

To sort an array of numbers in ascending or descending numerical order, you need to provide a compare function to the sort() method. The compare function determines the order of the elements.


// Ascending numerical order
const numbers = [5, 2, 9, 1, 5, 6];
numbers.sort((a, b) => a - b);
console.log(numbers); // Output: [1, 2, 5, 5, 6, 9]

// Descending numerical order
numbers.sort((a, b) => b - a);
console.log(numbers); // Output: [9, 6, 5, 5, 2, 1]

In this example:

The compare function (a, b) => a - b sorts the array in ascending numerical order.
The compare function (a, b) => b - a sorts the array in descending numerical order.

Sorting Arrays Alphabetically

To sort an array of strings alphabetically, you can use the sort() method without any arguments. By default, it will sort strings in ascending order.


// Alphabetical sorting
const fruits = ['Banana', 'Apple', 'Cherry', 'Mango'];
fruits.sort();
console.log(fruits); // Output: ['Apple', 'Banana', 'Cherry', 'Mango']

In this example:

The sort() method sorts the strings alphabetically in ascending order.

Custom Sorting with Objects

When sorting arrays of objects, you can provide a custom compare function to sort based on object properties.


// Array of objects
const people = [
  { name: 'John', age: 30 },
  { name: 'Jane', age: 25 },
  { name: 'Mike', age: 35 }
];

// Sort by age (ascending)
people.sort((a, b) => a.age - b.age);
console.log(people);
// Output: [{ name: 'Jane', age: 25 }, { name: 'John', age: 30 }, { name: 'Mike', age: 35 }]

// Sort by name (alphabetical)
people.sort((a, b) => a.name.localeCompare(b.name));
console.log(people);
// Output: [{ name: 'Jane', age: 25 }, { name: 'John', age: 30 }, { name: 'Mike', age: 35 }]

In this example:

The compare function (a, b) => a.age - b.age sorts the array of objects by age in ascending order.
The compare function a.name.localeCompare(b.name) sorts the array of objects alphabetically by name.

Conclusion

JavaScript's sort() method is versatile for sorting arrays of numbers and strings. By providing custom compare functions, you can sort arrays in various ways, including numerical and alphabetical orders. Understanding these sorting techniques will help you effectively organize and manipulate data in your JavaScript applications.