How to Sort a Map by Keys in JavaScript

How to Sort a Map by Keys in JavaScript ?

Answer

To sort a map by keys in JavaScript, you can convert the map to an array of key-value pairs, sort the array, and then convert it back to a map. This method provides a straightforward way to ensure the map is sorted by keys.

✐ Examples

1 Sorting a Map by Keys Using Array Conversion

We can sort a map by keys in JavaScript by converting the map to an array of key-value pairs, sorting the array by keys, and then converting it back to a map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We convert the map to an array of key-value pairs using the Array.from method.
We sort the array by keys using the sort method.
We create a new map from the sorted array using the Map constructor.
We print the sorted map to the console using the console.log function to verify the sorting.

JavaScript Program

const myMap = new Map([
    ['c', 3],
    ['a', 1],
    ['b', 2]
]);

// Convert the map to an array of key-value pairs
const sortedArray = Array.from(myMap).sort((a, b) => a[0].localeCompare(b[0]));

// Create a new map from the sorted array
const sortedMap = new Map(sortedArray);

// Print the sorted map
console.log('Sorted Map by Keys:', Array.from(sortedMap));

Output

Sorted Map by Keys: [['a', 1], ['b', 2], ['c', 3]]

2 Sorting a Map by Keys in Descending Order

We can sort a map by keys in descending order in JavaScript by converting the map to an array of key-value pairs, sorting the array by keys in descending order, and then converting it back to a map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We convert the map to an array of key-value pairs using the Array.from method.
We sort the array by keys in descending order using the sort method with a custom comparator.
We create a new map from the sorted array using the Map constructor.
We print the sorted map to the console using the console.log function to verify the sorting.

JavaScript Program

const myMap = new Map([
    ['c', 3],
    ['a', 1],
    ['b', 2]
]);

// Convert the map to an array of key-value pairs
const sortedArray = Array.from(myMap).sort((a, b) => b[0].localeCompare(a[0]));

// Create a new map from the sorted array
const sortedMap = new Map(sortedArray);

// Print the sorted map
console.log('Sorted Map by Keys (Descending):', Array.from(sortedMap));

Output

Sorted Map by Keys (Descending): [['c', 3], ['b', 2], ['a', 1]]

3 Sorting a Map with Numeric Keys

We can sort a map with numeric keys in JavaScript by converting the map to an array of key-value pairs, sorting the array by keys, and then converting it back to a map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has numeric keys and string values.
We convert the map to an array of key-value pairs using the Array.from method.
We sort the array by numeric keys using the sort method.
We create a new map from the sorted array using the Map constructor.
We print the sorted map to the console using the console.log function to verify the sorting.

JavaScript Program

const myMap = new Map([
    [3, 'three'],
    [1, 'one'],
    [2, 'two']
]);

// Convert the map to an array of key-value pairs
const sortedArray = Array.from(myMap).sort((a, b) => a[0] - b[0]);

// Create a new map from the sorted array
const sortedMap = new Map(sortedArray);

// Print the sorted map
console.log('Sorted Map by Keys:', Array.from(sortedMap));

Output

Sorted Map by Keys: [[1, 'one'], [2, 'two'], [3, 'three']]

Summary

In this tutorial, we learned How to Sort a Map by Keys in JavaScript language with well detailed examples.

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