CODEWITHSUNDEEP
javascriptobject
ChinaMahjongKing
ChinaMahjongKing

Reputation: 173

How did my JavaScript code get an undefined result?

I was practicing creating an object in JS and created the following object:

const jonas = {
    firstName: 'Jonas',
    lastName: 'Schmedtmann',
    birthYear: 1991,
    job: 'teacher',
    friends: ['Michael', 'Peter', 'Steven'],
    hasDriversLicense: false,

    calcAge: function () {
        this.age = 2037 - this.birthYear;
        return this.age;
    },
  };

A strange thing happen when I want to print the output of the function calcAge with the following code:

console.log(jonas.age);

The browser outputs "undefined" for the console.log() command.

Can anyone tell me where I got it wrong?

Thanks!

Upvotes: -1

Views: 75

Answers (2)

Bhavin Kariya
Bhavin Kariya

Reputation: 87

console.log(jonas.calcAge()); will give you the value of age

or

jonas.age = jonas.calcAge();

then

console.log(jonas.age);

Upvotes: 0

saurabh
saurabh

Reputation: 2713

const jonas = {
    firstName: 'Jonas',
    lastName: 'Schmedtmann',
    birthYear: 1991,
    job: 'teacher',
    friends: ['Michael', 'Peter', 'Steven'],
    hasDriversLicense: false,

    calcAge: function () {
        this.age = 2037 - this.birthYear;
        return this.age;
    },
  };

here calcAge is a function declaration that will add age property to the object by accessing the birthYear property of the same object. Everything sounds good but this all going to happen only if the function is called/executed.

function declaration and function call/execution is two different thing. so the console output is undefined as the function is never called

so need to call the function

jonas.calcAge()

Upvotes: 1

Related Questions