JavaScript How to Convert Map to Object Easily

Use Object.fromEntries(yourMap) to convert a Map to an Object in JavaScript, where yourMap is the Map you want to convert.

Examples

Inputnew Map([['a', 1], ['b', 2]])

Output{"a":1,"b":2}

Inputnew Map([[1, 'one'], [2, 'two']])

Output{"1":"one","2":"two"}

Inputnew Map()

Output{}

How to Think About It

To convert a Map to an Object, think of the Map as a list of key-value pairs. You want to take each pair and make it a property in a new Object. JavaScript provides a built-in method to do this easily by turning the Map entries into an Object's properties.

Algorithm

1

Get the Map you want to convert.

2

Use Object.fromEntries() and pass the Map to it.

3

Return the new Object created from the Map entries.

Code

javascript

const myMap = new Map([['name', 'Alice'], ['age', 25]]);
const obj = Object.fromEntries(myMap);
console.log(obj);

Output

{"name":"Alice","age":25}

Dry Run

Let's trace converting Map([['name', 'Alice'], ['age', 25]]) to an Object.

1

Start with Map

Map entries: [['name', 'Alice'], ['age', 25]]

2

Convert with Object.fromEntries

Object.fromEntries converts each pair to a property

3

Resulting Object

{"name":"Alice", "age":25}

Map Key	Map Value	Object Property	Object Value
name	Alice	name	Alice
age	25	age	25

Why This Works

Step 1: Map stores key-value pairs

A Map holds pairs like ['key', 'value'] which can be converted to object properties.

Step 2: Object.fromEntries converts pairs

The Object.fromEntries() method takes these pairs and creates an object with keys and values.

Step 3: Result is a plain object

The output is a normal JavaScript object with properties matching the Map's keys and values.

Alternative Approaches

Using a for-of loop

javascript

const myMap = new Map([['x', 10], ['y', 20]]);
const obj = {};
for (const [key, value] of myMap) {
  obj[key] = value;
}
console.log(obj);

More manual but works in older environments without Object.fromEntries.

Using Array.reduce

javascript

const myMap = new Map([['a', 1], ['b', 2]]);
const obj = [...myMap].reduce((acc, [key, value]) => {
  acc[key] = value;
  return acc;
}, {});
console.log(obj);

Uses array methods to build the object, useful if you want to transform keys or values.

Complexity: O(n) time, O(n) space

Time Complexity

The conversion loops through all Map entries once, so it takes linear time relative to the number of entries.

Space Complexity

A new object is created with the same number of properties as the Map entries, so space grows linearly.

Which Approach is Fastest?

Using Object.fromEntries() is generally fastest and most readable; manual loops or reduce add more code but similar performance.

Approach	Time	Space	Best For
Object.fromEntries	O(n)	O(n)	Simple and modern code
For-of loop	O(n)	O(n)	Older environments without Object.fromEntries
Array.reduce	O(n)	O(n)	When transforming keys or values during conversion