[[TOC]]

Objects

---

This is how you create an object:

• Use camelCase for property names

const user = {
    id: 12345,
    firstName: "Solomon",
    lastName: "Stroup",
    age: 38
};

Dot Notation

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You can use dot notation to "walk" through the object

user.id; // 12345
user.firstName; // "Solomon"
user.isAdmin; // undefined (property does not exist)

Redefining an object - updating its value

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const user = {
    id: 12345,
    firstName: "Solomon",
    lastName: "Stroup",
    age: 38
};
user.lastName = "Funkhouser"; //Assuming I take my girlfriend's last name. 
user.age = user.age + 1;
console.log(user); // {id: 12345, firstName: "Solomon", lastName: "Funkhouser", age: 39}

Things to remember:

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• An object is a data type that allows you to group several variables together into one variable that contains keys and values.
• Use camelCase for property names (for example firstName instead of first_name).
• To read or update the value of a property, you can use the dot notation.

Define an object and return it in a function

---

function getProductDetails() {
    const product = {
        id: 3,
        title: "The Product!",
        inStock: true
    }
    return product
}

console.log(getProductDetails()); // the object you define

Getting and returning values from an object

---

/**
 * @param {Object} city
 * @param {string} city.name
 * @param {number} city.value
 */
function getWeather(city) {
    return `It's currently ${city.value} degrees in ${city.name}`

}

console.log(getWeather({name: "Amsterdam", value: 3})); // "It's currently 3 degrees in Amsterdam"
console.log(getWeather({name: "Brasilia", value: 24})); // "It's currently 24 degrees in Brasilia"

Incrementing values within an object

---

This one adds and returns the new object. Notice that const doesn't make the object immutable

function incrementAge(person) {
    person.age = person.age + 1;
    return person;
}

// Sample usage - do not modify
const person = {
    firstName: "Sam",
    lastName: "Doe",
    age: 18
}

Returning some html with variables

---

/**
 * @param {Object} details
 * @param {string} details.title
 * @param {number} details.value
 */
export function renderTableRow(details) {
    return `<tr>
                <td>${details.title}</td>
                <td>${details.value}g</td>
            </tr>`
}

Working with an API and dot walking through the objects to get what you need.

---

The console.logs below don't work, they are used to traverse the objects returned from the API.

/** @param {Object} data */
export function getCountry(data) {
    return(data.location.country)
     console.log(data.location.country);
}

/** @param {Object} data */
export function getIcon(data) {
    return(data.current.weather_icons[0])
    console.log(data.current.weather_icons[0]);
}

/** @param {Object} data */
export function getTemperature(data) {
    return data.current.temperature;
    console.log(data.current.temperature);
}

Review

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• An object is a data type that allows you to group several variables together into one variable that contains keys and values.
• In JavaScript, the recommended convention is camelCase for property names (for example firstName instead of first_name).
• To read or update the value of a property, you can use the dot notation.