How to check if an object has a specific property in JavaScript?

In JavaScript, you can check if an object has a specific property using various methods, such as the hasOwnProperty() method, the in operator, or using the Object.keys() method.

Here’s how you can achieve it using these methods:

Using the hasOwnProperty() method

The hasOwnProperty() method checks if an object has a property with the specified name. It returns true if the object has the property directly on itself (not inherited from its prototype chain), otherwise it returns false.

const obj = { name: "John", age: 30 };

console.log(obj.hasOwnProperty("name")); // Output: true
console.log(obj.hasOwnProperty("gender")); // Output: false

Using the in operator

The in operator checks if an object has a property with the specified name, including properties inherited from its prototype chain. It returns true if the property exists, otherwise it returns false.

const obj = { name: "John", age: 30 };

console.log("name" in obj); // Output: true
console.log("gender" in obj); // Output: false

Using the Object.keys() method

The Object.keys() method returns an array of a given object’s own enumerable property names. You can then check if the property exists by searching for its name in the array.

const obj = { name: "John", age: 30 };

console.log(Object.keys(obj).includes("name")); // Output: true
console.log(Object.keys(obj).includes("gender")); // Output: false