Array Method - Sort

The sort() method sorts the elements of an array in place and returns the sorted array.

By default, the sorting order is ascending for numbers and according to Unicode sorting order for strings.

You can change the sorting order by providing a compareFunction that defines the sort order.

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const fruits = ['cherry', 'apple', 'banana'];
fruits.sort();

console.log(fruits); // ['apple', 'banana', 'cherry']

Here, 'cherry', 'apple', 'banana' are sorted alphabetically based on their Unicode positions.

By default, sort converts numbers into strings and then sorts them.

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const numbers = [10, 2, 33, 14];
numbers.sort();

console.log(numbers); // [10, 14, 2, 33]

When 10, 2, 33, 14 are converted to strings and sorted, strings that start with the character '1' appear first, which is why the array does not sort as expected to [2, 10, 14, 33].

To sort an array of numbers in ascending order, you need to specify a sorting criteria using compareFunction.

The compareFunction is used as arr.sort(compareFunction), and it defines a criteria for sorting the array elements.

This function accepts two arguments, and if it returns a value less than 0, the first argument is sorted before the second argument.

If it returns 0, their order is unchanged. If it returns a value greater than 0, the second argument is sorted before the first.

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const numbers = [10, 2, 33, 14];

// compareFunction: (a, b) => a - b
numbers.sort((a, b) => a - b); // Ascending order sort

console.log(numbers); // [2, 10, 14, 33]

Here, the compareFunction is (a, b) => a - b.

The function first compares 10 and 2. Since 10 - 2 is 8 (greater than 0), 2 is sorted before 10.

Next, 10 is compared to 33. Since 10 - 33 is -23 (less than 0), 10 is sorted before 33.

Following these comparisons, the numbers array is sorted to [2, 10, 14, 33].

In JavaScript, objects don't have a natural order. To sort objects in an array based on a specific key, use compareFunction as shown below.

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const students = [
  { name: 'John', height: 170 },
  { name: 'Alice', height: 160 },
  { name: 'Michael', height: 175 },
];

// Sort students by height in ascending order
students.sort((a, b) => a.height - b.height);

console.log(students);

Here, students are sorted by their height property in ascending order.