JavaScript: Set (In-Depth)

Set is a built-in JavaScript object that stores unique values of any type. Sets are useful for removing duplicates and fast membership checks.

Creating a Set

const set = new Set();
set.add(1);
set.add(2);
set.add(1); // Duplicate, ignored
    

Initializing from an Array

let arr = [1, 2, 2, 3, 4, 4];
let unique = new Set(arr);
[...unique]; // [1, 2, 3, 4]
    

Common Set Methods

• add(value): Adds a value.
• delete(value): Removes a value.
• has(value): Checks if a value exists.
• clear(): Removes all values.
• size: Returns the number of unique values.

const s = new Set([10, 20]);
s.has(10); // true
s.delete(20); // true
s.size; // 1
s.clear();
    

Iterating Over a Set

for (let item of unique) {
  console.log(item);
}
    

Use Cases for Sets

• Removing duplicates from arrays
• Checking for unique values
• Efficient membership testing
• Set operations: union, intersection, difference (with spread and array methods)