Reading Properties

An object is only useful if you can get its values back. To read a property, write the object's name, a dot and the key:

const book = {
    title: "The Hobbit",
    author: "J. R. R. Tolkien",
    pages: 310
};

console.log(book.title);
console.log(book.pages);

The Hobbit
310

You already know the dot from arrays: list.length reads the property length of an array.

book.title is a value like any other. You can store it in a variable, calculate with it or put it in a template literal:

const book = { title: "The Hobbit", author: "J. R. R. Tolkien", pages: 310 };

const days = book.pages / 10;
console.log(`${book.title} by ${book.author}`);
console.log("At 10 pages a day, you'll read it in", days, "days.");

The Hobbit by J. R. R. Tolkien
At 10 pages a day, you'll read it in 31 days.

What if you read a property the object doesn't have? Unlike a misspelled variable name, it isn't an error. You get undefined, the special value you know from arrays, which means “nothing is here”:

const book = { title: "The Hobbit", author: "J. R. R. Tolkien", pages: 310 };

console.log(book.year);
console.log(book.Title);

undefined
undefined

The book has no year. And Title is not title: as with variable names, uppercase and lowercase letters in keys matter. So when you see an undefined you didn't expect, check how you spelled the key.

One more mistake: the key after the dot has no quotes. book."title" ends with SyntaxError: Unexpected string.