Set Data Sturcture

A Set is similar to an array but automatically removes duplicate values.

Key methods:

• add
• size
• has
• delete
• clear

const numberSet = new Set([1,1,2,2,3,3]);
console.log(numberSet); // Set {1, 2, 3}
console.log(numberSet.size); // 3

numberSet.add(4).add(5);
console.log(numberSet.has(4)); // true
console.log(numberSet.delete(4)); // true
numberSet.clear();

Iteration Methods

const colors = new Set(['red', 'green', 'blue']);

// Keys and values are identical in Sets
for (const color of colors.keys()) {
  console.log(color);
}

colors.forEach((value, key) => {
  console.log(key, value);
});

Advanced Deduplicasion

function removeDuplicates(arr) {
  const seen = new Set();
  return arr.filter(item => {
    const identifier = JSON.stringify(item);
    return seen.has(identifier) ? false : seen.add(identifier);
  });
}

Map Data Srtucture

Maps store key-value pairs where keys can be any data type.

const userMap = new Map([
  ['name', 'Alex'],
  ['age', 30],
  [{'id': 1}, 'Admin']
]);

Key methods:

• set
• get
• has
• delete
• clear

userMap.set('role', 'Developer');
console.log(userMap.get('age')); // 30
console.log(userMap.has('name')); // true
userMap.delete('name');
userMap.clear();

Iteration Methods

for (const key of userMap.keys()) {
  console.log(key);
}

for (const [key, value] of userMap.entries()) {
  console.log(key, value);
}

userMap.forEach((value, key) => {
  console.log(key, value);
});