JavaScript Set entries()
Syntax & Examples

Set.entries() method

The entries() method of the Set object in JavaScript returns a new iterator object that contains an array of [value, value] for each element in the Set object, in insertion order. This is similar to the Map object, so that each entry's key is the same as its value for a Set.

Syntax of Set.entries()

The syntax of Set.entries() method is:

entries()

This entries() method of Set returns a new iterator object that contains an array of [value, value] for each element in the Set object, in insertion order. This is similar to the Map object, so that each entry's key is the same as its value for a Set.

Return Type

Set.entries() returns value of type Iterator.


✐ Examples

1 Using entries() to iterate over a Set

In JavaScript, we can use the entries() method to get an iterator object and use it to iterate over the elements of a Set.

For example,

  1. Create a new Set object letters with initial values 'a', 'b', and 'c'.
  2. Use the entries() method to get an iterator object iterator for the letters Set.
  3. Use a for...of loop to iterate over the iterator and log each entry to the console using console.log().

JavaScript Program

const letters = new Set(['a', 'b', 'c']);
const iterator = letters.entries();
for (const entry of iterator) {
  console.log(entry);
}

Output

[ 'a', 'a' ]
[ 'b', 'b' ]
[ 'c', 'c' ]

2 Using entries() to convert a Set to an array of arrays

In JavaScript, we can use the entries() method to convert a Set object to an array of [value, value] arrays.

For example,

  1. Create a new Set object numbers with initial values 1, 2, and 3.
  2. Use the entries() method to get an iterator object iterator for the numbers Set.
  3. Convert the iterator to an array using the Array.from() method and store it in the variable arrayOfEntries.
  4. Log arrayOfEntries to the console using console.log().

JavaScript Program

const numbers = new Set([1, 2, 3]);
const iterator = numbers.entries();
const arrayOfEntries = Array.from(iterator);
console.log(arrayOfEntries);

Output

[ [ 1, 1 ], [ 2, 2 ], [ 3, 3 ] ]

3 Using entries() with a Set of objects

In JavaScript, we can use the entries() method to iterate over a Set object containing objects.

For example,

  1. Create a new Set object people with initial objects representing different people.
  2. Use the entries() method to get an iterator object iterator for the people Set.
  3. Use a for...of loop to iterate over the iterator and log each entry to the console using console.log().

JavaScript Program

const person1 = { name: 'John' };
const person2 = { name: 'Jane' };
const people = new Set([person1, person2]);
const iterator = people.entries();
for (const entry of iterator) {
  console.log(entry);
}

Output

[ { name: 'John' }, { name: 'John' } ]
[ { name: 'Jane' }, { name: 'Jane' } ]

Summary

In this JavaScript tutorial, we learned about entries() method of Set: the syntax and few working examples with output and detailed explanation for each example.