JavaScript Array sort() Method

The sort() method in JavaScript arranges the elements of an array in place and returns the sorted array. By default, it sorts elements alphabetically, treating them as strings.

However, for numerical sorting, you can provide a custom comparison function. This function dictates the sorting criteria, allowing precise control over the sorting process. `sort()` enhances the efficiency and functionality of JavaScript applications by enabling you to organize array elements according to specific requirements in a professional and formal manner.

Syntax

arr.sort(compareFunction);

Parameters

• array: The array to be sorted.
• compareFunction (Optional): A function that defines the sort order. If omitted, the array elements are sorted based on their string Unicode code points.

Return value

This method returns the reference of the sorted original array.

Examples:

Example 1: Sorting an array of strings

This example shows the use of the sort() function.

// JavaScript to illustrate sort() function
function func() {

    // Original string
    let arr = ["Geeks", "for", "Geeks"]

    console.log(arr);
    // Sorting the array
    console.log(arr.sort());
}
func();

[ 'Geeks', 'for', 'Geeks' ]
[ 'Geeks', 'Geeks', 'for' ]

Explanation:

The sort() method rearranges the elements of the arr array alphabetically, producing the output ["Geeks", "Geeks", "for"].

Example 2: Sorting an array of numbers without compare function

Here, the sort() method arranges the elements of the array in ascending order.

// JavaScript to illustrate sort() function
function func() {
    //Original string
    let arr = [2, 5, 8, 1, 4]

    //Sorting the array
    console.log(arr.sort());
}
func();

[ 1, 2, 4, 5, 8 ]

Explanation:

The sort() method is called on an array of numbers [2, 5, 8, 1, 4]. The sort() method will sort the elements alphabetically because no comparison function is provided. Therefore, the output will be [1, 2, 4, 5, 8], which is sorted alphabetically based on the string representations of the numbers.

Example 3: Sorting numeric value without compare function

Here, we are sorting numeric value without compare function

let numbers = [20, 5.2, -120, 100, 30, 0]
console.log(numbers.sort())

[ -120, 0, 100, 20, 30, 5.2 ]

Explanation:

When you use the sort() method without a compare function, JavaScript sorts array elements as strings by default, which may not always produce the expected results for numeric arrays. Let’s break down the sorting process:

• JavaScript converts each element of the array to a string.
• It then compares the UTF-16 code units of each character in the strings and sorts them based on the Unicode code point value.

Here’s what happens with your array:

• The numbers are converted to strings: ["20", "5.2", "-120", "100", "30", "0"].
• When sorted alphabetically, -120 comes first because - has a lower Unicode code point value than digits (0 to 9). Then comes 0, followed by 100, 20, 30, and 5.2.

Example 4: Sorting numeric value with compare function

We can resolve the unexpected error that occurred in the above example by using the sort() method for numerics using the following compare function.

let numbers = [20, 5.2, -120, 100, 30, 0];

/* Logic: 
   20 - (5.2) = +ve => 5.2 would be placed before 20,
   20 - (-120) = +ve => -120 would be placed before 20,
   20 - (100) = -ve => 100 would be placed after 20,
   20 - (30) = -ve => 30 would be placed after 20,
   20 - (0) = +ve => 0 would be placed before 20,
   Similarly for every element, we check 
   and place them accordingly in iterations.
*/

function compare(a, b) {
    return a - b;
}
console.log(numbers.sort(compare));

[ -120, 0, 5.2, 20, 30, 100 ]

Explanation:

• The compare function subtracts b from a. If the result is negative, a comes before b in the sorted array; if positive, b comes before a; if zero, their relative order remains unchanged.
• By providing this custom comparison function to the sort() method, JavaScript sorts the array numbers based on the numerical values of its elements.

Please go through this How to Sort Numeric Array using JavaScript?, to know how the javascript array sort function works 

We have a complete list of Javascript Array methods, to check those please go through this Javascript Array Complete reference article.

Supported Browsers:

• Google Chrome
• Edge
• Internet Explorer 
• Firefox
• Opera
• Safari

JavaScript Array sort() Method- FAQs

What is the use of the array sort () method in JavaScript?

The sort() method arranges the elements of an array in place and returns the sorted array. By default, it sorts elements as strings and converts elements to strings if they are not already.

What does array sort () return?

The sort() method in JavaScript returns the sorted array after arranging its elements according to the default or provided sorting order. It modifies the original array and does not create a new one.

What is the time complexity of the sort() method in JavaScript?

The time complexity of sort() is generally O(n log n), where n is the number of elements in the array. However, this can vary based on the implementation and browser.

Does sort() modify the original array?

Yes, sort() modifies the original array. It sorts the elements of the array in place and returns the sorted array.

Does sort() handle edge cases like undefined or null values?

Yes, sort() handles undefined and null values by treating them as undefined when comparing (ECMAScript specification).

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