How to loop through object keys using Object.keys() in JavaScript

published: 27 Apr 2022

2 min read

The Object.keys() method was introduced in ES6. It takes the object that you want to iterate over as an argument and returns an array containing all properties names (also known as keys).

You can then use any of the array looping methods, such as forEach(), to iterate through the array and retrieve the value of each property.

Here is an example that uses the Object.keys() method to iterate over the keys and values of an object:

const courses = {
  java: 10,
  javascript: 55,
  nodejs: 5,
  php: 15
}

// convert object to key's array
const keys = Object.keys(courses)

// print all keys
console.log(keys)
// [ 'java', 'javascript', 'nodejs', 'php' ]

// iterate over object
keys.forEach(key => {
  console.log('${key}: ${courses[key]}')
})

// java: 10
// javascript: 55
// nodejs: 5
// php: 15

In the above function declaration, I used ES6 syntax. I assume that you are already familiar with ES6 arrow functions. If you are new to ES6, read the arrow functions guide to learn about it.

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How to loop through object keys using Object.keys() in JavaScript

The Object.keys() method was introduced in ES6. It takes the object that you want to iterate over as an argument and returns an array containing all properties names (also known as keys).

You can then use any of the array looping methods, such as forEach(), to iterate through the array and retrieve the value of each property.

Here is an example that uses the Object.keys() method to iterate over the keys and values of an object:

const courses = {
  java: 10,
  javascript: 55,
  nodejs: 5,
  php: 15
}

// convert object to key's array
const keys = Object.keys(courses)

// print all keys
console.log(keys)
// [ 'java', 'javascript', 'nodejs', 'php' ]

// iterate over object
keys.forEach(key => {
  console.log('${key}: ${courses[key]}')
})

// java: 10
// javascript: 55
// nodejs: 5
// php: 15

In the above function declaration, I used ES6 syntax. I assume that you are already familiar with ES6 arrow functions. If you are new to ES6, read the arrow functions guide to learn about it.