In this article we will learn how to check if a key exists in object in JavaScript.
It is very common to check if a key exists in object in JavaScript in JavaScript.
Problem
Now we have a problem which is that we want to check if a key exists in object.
Imagine we have object like this:
const myObject = {
name: "John",
age: 30,
country: "USA"
}
And we want to check if name
key is exists on this object or not.
Expected output will be:
true
Because key is exists.
How to solve this problem?
This problem is easy, and there is more than one solution to it, and we will explain all the solutions in detail, such as:
- Using
in
operator. - Using Optional Chaining
- Using
Object.hasOwn
Check if key exists using in
operator
We can use in
operator to check if key exists or not.
Let's see an example
// Object
const myObject = {
name: "John",
age: 30,
country: "USA"
}
// Tests:
console.log('name' in myObject);
console.log('age' in myObject);
console.log('skills' in myObject);
console.log('country' in myObject);
Output
true
true
false
true
Check if key exists using Optional Chaining
WE can use optional chaining to check if key exists in object as well.
Example
// Object
const myObject = {
name: "John",
age: 30,
country: "USA"
}
// Tests
console.log(myObject?.name);
console.log(myObject?.age);
console.log(myObject?.skills);
console.log(myObject?.country);
Output
John
30
undefined
USA
Check if key exists using Object.hasOwn
We can use Object.hasOwn
method to solve our problem as well.
Let's see an example
// Object
const myObject = {
name: "John",
age: 30,
country: "USA"
}
// Tests:
console.log(Object.hasOwn(myObject, 'name'));
console.log(Object.hasOwn(myObject, 'age'));
console.log(Object.hasOwn(myObject, 'skills'));
console.log(Object.hasOwn(myObject, 'country'));
Output
true
true
false
true
Thank you for reading
Thank you for reading my blog. 🚀