JavaScript Object.entries()

Summary: in this tutorial, you will learn how to use the JavaScript Object.entries() method.

Introduction to JavaScript Object.entries() method #

ES2017 introduces the Object.entries() method that accepts an object and returns its own enumerable string-keyed property [key, value] pairs of the object.

Here is the syntax of the Object.entries() method:

Object.entries()Copy

See the following example:

const ssn = Symbol('ssn');
const person = {
    firstName: 'John',
    lastName: 'Doe',
    age: 25,
    [ssn]: '123-345-789'
};

const kv = Object.entries(person);

console.log(kv);Copy

Output:

[
    ['firstName', 'John'],
    ['lastName', 'Doe'],
    ['age', 25]
]Copy

In this example:

• The firstName, lastName, and age are own enumerable string-keyed property of the person object, therefore, they are included in the result.
• The ssn is not a string-key property of the person object, so it is not included in the result.

Object.entries() vs. for…in #

The main difference between the Object.entries() and the for...in loop is that the for...in loop also enumerates object properties in the prototype chain.