Map and Set in JavaScript

The Map and Set data structures were introduced in ECMAScript 2015 (ES6) and are designed for more flexible and powerful data storage compared to regular objects and arrays.

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Map

Map is a collection of key-value pairs. It's similar to an object but has several advantages.

  
const myMap = new Map();

myMap.set("name", "Ani");
myMap.set("age", 30);

console.log(myMap.get("name")); // Ani
console.log(myMap.has("age")); // true
console.log(myMap.size); // 2

myMap.delete("age");
console.log(myMap.has("age")); // false
  

Features and advantages:

• Keys can be of any type - not just strings or symbols (including objects, functions)
• Maintains insertion order
• More performant for frequent key lookups
• Requires working with .set, .get, .has, .delete methods

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Set

Set is a collection of values where duplicate values are not allowed.

  
const mySet = new Set();

mySet.add(1);
mySet.add(2);
mySet.add(2); // Will be ignored because it already exists

console.log(mySet.has(1)); // true
console.log(mySet.size); // 2

mySet.delete(2);
console.log(mySet.has(2)); // false
  

Features and advantages:

• Stores only unique values (no duplicates)
• More convenient for filtering and membership checking
• Can contain any type of data - primitive or objects

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Difference Between Object/Array vs Map/Set

Property	Object / Array	Map / Set
Key/value types	string or number	Any (objects, functions)
Maintains insertion order	Not always	Yes
Data lookup speed	Slow for large amounts	Fast
Duplicate values	Allowed	Set - no, Map - keys are unique

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Conclusion

Map is the best choice when you need to store key-value pairs, while Set is ideal when you need to store only unique values. They are more convenient and performant than regular objects and arrays, especially when managing complex data.

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