Clean • Professional
A Set in JavaScript provides several built-in methods to add, remove, check, and iterate over elements.
add()Adds a new value to the Set. Duplicate values are ignored.
const numbers = new Set();
numbers.add(1);
numbers.add(2);
numbers.add(2); // Duplicate ignored
console.log(numbers); // Set { 1, 2 }
delete()Removes a specific value from the Set.
true if the value existed and was removed.false if the value did not exist.const numbers = new Set([1, 2, 3]);
numbers.delete(2);
console.log(numbers); // Set { 1, 3 }
has()Checks if a value exists in the Set.
const numbers = new Set([1, 2, 3]);
console.log(numbers.has(2)); // true
console.log(numbers.has(4)); // false
clear()Removes all elements from the Set.
const numbers = new Set([1, 2, 3]);
numbers.clear();
console.log(numbers); // Set {}
sizeReturns the number of unique elements in the Set.
const numbers = new Set([1, 2, 3]);
console.log(numbers.size); // 3
6. entries()Returns an iterator of [value, value] pairs (for Map compatibility).
const numbers = new Set([1, 2]);
console.log([...numbers.entries()]); // [[1,1],[2,2]]
7. keys()Returns an iterator of the Set’s values (same as values()).
console.log([...numbers.keys()]); // [1, 2]
8. values()Returns an iterator of the Set’s values (redundant with keys() but part of the API).
console.log([...numbers.values()]); // [1, 2]
Sets are iterable. You can loop over them using:
a. for...of Loop
const numbers = new Set([1, 2, 3]);
for (const num of numbers) {
console.log(num);
}
// Output: 1, 2, 3
b. forEach() Method
numbers.forEach((value) => console.log(value));
// Output: 1, 2, 3
c. Spread Operator
const numbersArray = [...numbers];
console.log(numbersArray); // [1, 2, 3]
Sets can be easily converted to arrays for further operations:
const numbers = new Set([1, 2, 3]);
const numbersArray = Array.from(numbers);
console.log(numbersArray); // [1, 2, 3]
| Method / Property | Description |
|---|---|
add(value) | Adds a new element to the Set |
delete(value) | Removes a specific element |
has(value) | Checks if a value exists |
clear() | Removes all elements |
size | Returns the number of elements |
forEach() | Executes a function for each element |
Spread / Array.from() | Convert Set to Array |