Object to Map conversion in JavaScript

In JavaScript, you can convert an object to a Map using several approaches. Maps offer advantages over objects like guaranteed key insertion order and the ability to use any data type as keys.

Suppose we have an object like this:

const obj = {
  name: "Jai",
  age: 32,
  occupation: "Software Engineer",
  address: "Dhindosh, Maharashtra",
  salary: "146000"
};

We need to convert this object into a Map while preserving all key-value pairs.

Using Object.entries() (Recommended)

The most concise approach uses Object.entries() with the Map constructor:

const obj = {
  name: "Jai",
  age: 32,
  occupation: "Software Engineer",
  address: "Dhindosh, Maharashtra",
  salary: "146000"
};

const objectToMap = (obj) => new Map(Object.entries(obj));

console.log(objectToMap(obj));

Map(5) {
  'name' => 'Jai',
  'age' => 32,
  'occupation' => 'Software Engineer',
  'address' => 'Dhindosh, Maharashtra',
  'salary' => '146000'
}

Using Manual Iteration

For more control, you can iterate through object keys manually:

const obj = {
  name: "Jai",
  age: 32,
  occupation: "Software Engineer"
};

const objectToMap = (obj) => {
  const map = new Map();
  for (const key in obj) {
    if (obj.hasOwnProperty(key)) {
      map.set(key, obj[key]);
    }
  }
  return map;
};

console.log(objectToMap(obj));

Map(3) {
  'name' => 'Jai',
  'age' => 32,
  'occupation' => 'Software Engineer'
}

Using Object.keys() with forEach

Another approach using Object.keys() and forEach():

const obj = {
  name: "Jai",
  age: 32
};

const objectToMap = (obj) => {
  const map = new Map();
  Object.keys(obj).forEach(key => {
    map.set(key, obj[key]);
  });
  return map;
};

console.log(objectToMap(obj));
console.log(objectToMap(obj).get('name')); // Access specific value

Map(2) { 'name' => 'Jai', 'age' => 32 }
Jai

Comparison

Key Benefits of Maps over Objects

const obj = { name: "Jai", age: 32 };
const map = new Map(Object.entries(obj));

// Size property
console.log("Object size:", Object.keys(obj).length);
console.log("Map size:", map.size);

// Key types
map.set(1, "number key");
map.set(true, "boolean key");
console.log(map);

Object size: 2
Map size: 2
Map(4) {
  'name' => 'Jai',
  'age' => 32,
  1 => 'number key',
  true => 'boolean key'
}

Conclusion

Use new Map(Object.entries(obj)) for the most concise object-to-Map conversion. Maps provide better performance for frequent additions/deletions and support any data type as keys.