Objects

Objects group related data

• An object stores named values together: { key: value, ... }.
• Reach a value by its key with a dot: person.name.
• An object is perfect for one thing that has several details.

let person = { name: "Ada", age: 36 };
console.log(person.name);   // → Ada
console.log(person.age);    // → 36

Change or add a property

• Assign to obj.key to change a value — or to add a brand-new one.

let car = { speed: 0 };
car.speed = 60;       // change an existing key
car.colour = "red";   // add a new key
console.log(car.speed);   // → 60

Watch out

• A missing key gives undefined, not an error: person.height → undefined.
• person["name"] does the same as person.name — handy when the key sits in a variable.

Common mistakes

• Read a value with obj.key or obj["key"].
• A missing key gives undefined, not an error.

Now you try

• Read and change object properties.
• Press Check answer to test it.