JavaScript Set Methods

JavaScript Set Methods

JavaScript Set Methods come with built-in methods to add, delete, check, loop, and manage unique values.

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📌 List of Common Set Methods

Method	Description
add()	Adds a new value
delete()	Removes a specific value
has()	Checks if a value exists
clear()	Removes all values
size	Returns number of elements (property, not a function)
forEach()	Iterates through set values
values()	Returns an iterator of values
keys()	Same as values() (for compatibility with Maps)
entries()	Returns [value, value] pairs (like Map)

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 1. add()

let set = new Set(); set.add(10); set.add(20); set.add(10); // Duplicate ignored console.log(set); // Set {10, 20}

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let set = new Set(); set.add(10); set.add(20); set.add(10); // Duplicate ignored console.log(set); // Set {10, 20}

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 2. delete()

set.delete(20); console.log(set); // Set {10}

1 2	set.delete(20); console.log(set); // Set {10}

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 3. has()

console.log(set.has(10)); // true console.log(set.has(50)); // false

1 2	console.log(set.has(10)); // true console.log(set.has(50)); // false

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 4. clear()

set.clear(); console.log(set); // Set {}

1 2	set.clear(); console.log(set); // Set {}

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 5. size (Property)

let numbers = new Set([1, 2, 3]); console.log(numbers.size); // 3

1 2	let numbers = new Set([1, 2, 3]); console.log(numbers.size); // 3

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 6. forEach()

numbers.forEach(value => console.log(value));

1	numbers.forEach(value => console.log(value));

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 7. values() Method

console.log(numbers.values()); // Iterator: {1, 2, 3}

1 2	console.log(numbers.values()); // Iterator: {1, 2, 3}

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 8. keys() Method (Same as values())

console.log(numbers.keys());

1	console.log(numbers.keys());

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 9. entries() Method

console.log(numbers.entries()); // Output: [1,1], [2,2], [3,3]

1 2	console.log(numbers.entries()); // Output: [1,1], [2,2], [3,3]

Useful when using Set where Map-like structure is needed.

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⭐ Example Using Multiple Methods

let fruits = new Set(["Apple", "Mango", "Banana"]); fruits.add("Orange"); fruits.delete("Mango"); console.log(fruits.has("Apple")); // true console.log(fruits.size); // 3 fruits.forEach(item => console.log(item));

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let fruits = new Set(["Apple", "Mango", "Banana"]);   fruits.add("Orange"); fruits.delete("Mango");   console.log(fruits.has("Apple")); // true console.log(fruits.size); // 3   fruits.forEach(item => console.log(item));

 

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⏳ Output:

true
3
Apple
Banana
Orange


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🧠 When to Use Sets?

✔ Removing duplicates
✔ Fast value lookup
✔ Unique collections (tags, IDs, categories)

• Next story JavaScript Set Logic
• Previous story JavaScript Sets

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