JavaScript Object.keys, Values, Entries

Object.keys(), Object.values(), and Object.entries() in JavaScript

JavaScript provides three powerful methods for working with objects:

• Object.keys(obj) → Returns an array of keys
• Object.values(obj) → Returns an array of values
• Object.entries(obj) → Returns an array of key-value pairs

1. Object.keys(obj) – Get Keys

This method returns an array of all the keys (property names) of an object.

Example

const user = { name: "Alice", age: 25, country: "USA" };

console.log(Object.keys(user)); 
// Output: ["name", "age", "country"]

Use Case

You can use Object.keys() to loop through an object:

Object.keys(user).forEach(key => {
    console.log(`${key}: ${user[key]}`);
});

Output:

name: Alice
age: 25
country: USA

2. Object.values(obj) – Get Values

This method returns an array of all the values in an object.

Example

console.log(Object.values(user)); 
// Output: ["Alice", 25, "USA"]

Use Case

Calculate the total sum of an object’s numeric values:

const salaries = { Alice: 5000, Bob: 7000, Charlie: 6000 };

const totalSalary = Object.values(salaries).reduce((sum, salary) => sum + salary, 0);
console.log(totalSalary); 
// Output: 18000

3. Object.entries(obj) – Get Key-Value Pairs

This method returns an array of key-value pairs, where each item is a sub-array [key, value].

Example

console.log(Object.entries(user));
/* Output:
[
  ["name", "Alice"],
  ["age", 25],
  ["country", "USA"]
]
*/

Use Case

Loop through an object using forEach():

Object.entries(user).forEach(([key, value]) => {
    console.log(`${key}: ${value}`);
});

Convert an Object into a Map

const userMap = new Map(Object.entries(user));
console.log(userMap.get("name")); // Output: Alice

When to Use Each Method?

Method	Returns	Use Case
Object.keys(obj)	Array of property names	Looping through keys, checking object properties
Object.values(obj)	Array of property values	Summing values, filtering data
Object.entries(obj)	Array of [key, value] pairs	Converting to Map, iterating with both keys and values

Summary

✔ Object.keys() → Extracts keys from an object.
✔ Object.values() → Extracts values from an object.
✔ Object.entries() → Extracts key-value pairs from an object.

These methods are useful for iterating over objects, transforming data, and working with dynamic keys! Let me know if you need more examples. 😊