In this lesson, you'll learn about built-in object methods in JavaScript, which provide powerful tools for creating, modifying, and interacting with objects. These methods help streamline working with objects and enhance your ability to manage data effectively.

Built-in Object Methods

Objects in JavaScript are collections of key-value pairs, capable of holding various data types, including strings, numbers, and booleans. All objects in JavaScript inherit from the parent constructor, which offers several built-in methods to simplify object manipulation. Unlike array methods like and , which are used on array instances, object methods are static and used directly on the constructor, taking the object instance as a parameter.

Key Built-in Object Methods

Object.create()

The method creates a new object linked to the prototype of an existing object. This is useful for extending objects without duplicating code.

const role = {
    title: 'developer',
    type: 'full-time',
    isOpen: true,
    showDetails() {
        const status = this.isOpen ? 'is open for applications' : "is not open for applications";
        console.log(`The ${this.title} role is ${this.type} and ${status}.`);
    }
};

const designer = Object.create(role);
designer.title = "designer";
designer.showDetails(); // The designer role is full-time and is open for applications.

Object.keys()

returns an array of an object's keys, allowing you to iterate over them or check their count.

const team = {
    leader: 'Alice',
    developer: 'Bob',
    designer: 'Charlie',
    tester: 'Dana'
};

const keys = Object.keys(team);
console.log(keys); // ["leader", "developer", "designer", "tester"]

keys.forEach(key => {
    console.log(`${key}: ${team[key]}`);
});

Object.values()

returns an array of an object's values, useful for iterating over or analyzing data.

const device = {
    brand: 'Samsung',
    model: 'Galaxy S21',
    year: 2021
};

const values = Object.values(device);
console.log(values); // ["Samsung", "Galaxy S21", 2021]

Object.entries()

returns a nested array of an object's key-value pairs, allowing for easy iteration and manipulation.

const software = {
    name: 'Photoshop',
    version: '2021',
    license: 'Commercial'
};

const entries = Object.entries(software);
entries.forEach(([key, value]) => {
    console.log(`${key}: ${value}`);
});

Object.assign()

copies values from one object to another, useful for merging objects.

const personalDetails = { firstName: 'Jane', lastName: 'Doe' };
const jobDetails = { position: 'Manager', company: 'Tech Inc' };

const profile = Object.assign({}, personalDetails, jobDetails);
console.log(profile); // {firstName: "Jane", lastName: "Doe", position: "Manager", company: "Tech Inc"}

Object.freeze()

prevents modifications to an object's properties and values, ensuring immutability.

const settings = { theme: 'light', notifications: true };
Object.freeze(settings);

settings.theme = 'dark'; // No effect
console.log(settings); // {theme: "light", notifications: true}

Object.seal()

prevents new properties from being added to an object but allows modification of existing properties.

const account = { username: 'user123', password: 'pass123' };
Object.seal(account);

account.password = 'newpass'; // Allowed
account.email = 'user@example.com'; // Not allowed
console.log(account); // {username: "user123", password: "newpass"}

Object.getPrototypeOf()

retrieves the prototype of an object, useful for understanding inheritance and prototype chains.

const gadgets = ['laptop', 'tablet', 'smartphone'];
console.log(Object.getPrototypeOf(gadgets) === Array.prototype); // true

Conclusion

JavaScript's built-in object methods provide essential tools for managing and manipulating objects, allowing you to create, modify, and protect data effectively. Understanding these methods enhances your ability to work with objects and leverage their full potential in your applications.

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