Check object variable exists when using object destructuring

April 25, 2022

I have a ‘getData’ function which gets passed a ‘data’ variable. Inside the function I’m trying to access an object ‘data.someObject’ which may or may not exist because it comes from an outside library.

What is the best approach to check if it does exist before trying to use it? Also see I’m using object destructuring here aswell.

const getData = (data) => {
    const { name, age } = data.someObject; // someObject may or may not exist
    console.log(name, age);
}

I thought doing this might work:

const { name, age } = data.someObject || {};

But I wasn’t sure if that would throw an error.

Thanks

>Solution :

You can use || & if required provide default values while destructuring.

function print(user) {
  const { fname = "Anonymous", lname = "Panda" } = user.fullname || {};

  console.log(`Hello ${fname} ${lname}`);
}

print({ fullname: { fname: "John", lname: "Doe" } });
print({});
print({ fullname: null });