> ## Documentation Index > Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt > Use this file to discover all available pages before exploring further. # TypeScript Set A `Set` in TypeScript is a generic, iterable collection of unique values. It wraps the native ECMAScript 6 `Set` object with TypeScript's static type system, ensuring that all elements within the collection conform to a specified type parameter ``. Uniqueness is evaluated using the SameValueZero algorithm, meaning `NaN` is considered equal to `NaN`, and duplicate values are silently ignored during insertion. ## Instantiation and Type Inference A `Set` can be instantiated empty with an explicit generic type argument, or initialized with an iterable object (like an Array), from which TypeScript will infer the type. ```typescript theme={"dark"} // Explicitly typed empty Set const stringSet = new Set(); // Type inferred as Set const numberSet = new Set([1, 2, 3, 3]); // Internal state: {1, 2, 3} // Union types const mixedSet = new Set(); ``` ## Core API The `Set` prototype provides a standard set of methods for mutation and inspection. * **`add(value: T): this`**: Appends a new element with the specified value. Returns the `Set` instance, enabling method chaining. * **`has(value: T): boolean`**: Evaluates whether an element with the specified value exists within the collection. * **`delete(value: T): boolean`**: Removes the specified element. Returns `true` if the element existed and was removed, or `false` if it did not exist. * **`clear(): void`**: Removes all elements from the `Set`. * **`size: number`**: A read-only property returning the total count of elements. ```typescript theme={"dark"} const registry = new Set(); // Mutation registry.add(100).add(200); // Inspection const exists = registry.has(100); // true const count = registry.size; // 2 // Deletion const removed = registry.delete(200); // true registry.clear(); // size is now 0 ``` ## Object Reference Equality When storing complex types (objects, arrays, functions), uniqueness is determined by memory reference, not structural equality. Two structurally identical objects are treated as distinct elements. ```typescript theme={"dark"} interface Config { retries: number; } const configSet = new Set(); const defaultConfig = { retries: 3 }; configSet.add(defaultConfig); configSet.add(defaultConfig); // Ignored, same reference configSet.add({ retries: 3 }); // Added, different reference console.log(configSet.size); // 2 ``` ## Iteration `Set` objects are natively iterable and maintain insertion order. They can be traversed using `for...of` loops or the built-in `forEach` method. ```typescript theme={"dark"} const tokens = new Set(['alpha', 'beta', 'gamma']); // Iterable protocol for (const token of tokens) { console.log(token); } // Callback-based iteration // Note: 'value' and 'key' are identical in Sets to maintain compatibility with Map's forEach signature. tokens.forEach((value: string, key: string, set: Set) => { console.log(value === key); // true }); ``` ## Native Set Operations (TypeScript 5.5+ / ES2024) Modern TypeScript supports native mathematical set operations, returning new `Set` instances without mutating the originals. ```typescript theme={"dark"} const evens = new Set([2, 4, 6, 8]); const primes = new Set([2, 3, 5, 7]); // Elements in either set const union = evens.union(primes); // Set {2, 4, 6, 8, 3, 5, 7} // Elements in both sets const intersection = evens.intersection(primes); // Set {2} // Elements in 'evens' but not in 'primes' const difference = evens.difference(primes); // Set {4, 6, 8} // Elements in either set, but not both const symmetricDifference = evens.symmetricDifference(primes); // Set {4, 6, 8, 3, 5, 7} // Boolean subset/superset checks const isSubset = new Set([2, 4]).isSubsetOf(evens); // true const isSuperset = evens.isSupersetOf(new Set([2])); // true ```

Tired of Poor TypeScript Skills? Fix That With Deep Grasping! Learn More