Object in Javascript

In Javascript, objects are a fundamental data type and are used to represent collections of key-value pairs.

Objects allow us to structure and organize data in a more complex and meaningful way.

Creating Objects In Javascript:

Object Literal In Javascript:

The most common way to create an object is using the object literal syntax, where we define key-value pairs inside curly braces `{}`.

Example:

let person = {
  name: "Alice",
  age: 35,
  isStudent: false
};

Object Constructor In Javascript:

We can create objects using the "new" keyword and assign values to the attributes.

Example:

let person = new Object();
person.name = "Alice";
person.age = 35;
person.isStudent = false;

console.log(person) //  { name: "Alice", age: 35, isStudent: false };

Accessing Object Properties In Javascript:

We can access object properties using dot (`.`) notation or square bracket (`[]`) notation.

Example:

console.log(person.name); // "Alice"
console.log(person["age"]); // 35
console.log(person["isStudent"]); // false

Modifying Object Properties In Javascript:

We can modify object properties using the `.` operator or by specifying the key name in square brackets `["keyName"]`.

Example:

person.age = 40;
person["isStudent"] = true;

Adding New Properties In Javascript Object:

We can add new properties in the object using the `.` operator or by specifying the key name in square brackets `["keyName"]`.

Example:

person.city = "London";
person["country"] = "England";

Nested Objects In Javascript:

Objects can contain other objects as properties.

Example:

let address = {
  street: "123 Main St, Park Avenue",
  city: "London",
  country: "England"
};

let person = {
  name: "Alice",
  age: 30,
  address: address
};

Methods In Javascript:

Properties in an object can also be functions, called methods.

Example:

let person = {
  name: "Alice",
  age: 30,
  getName: function() {
    return this.name;
  }
};

person.getName(); // "Alice"

In the above example, `this` keyword is referring to `person` object here.

Object Destructuring (ES6+) In Javascript:

We can extract properties from objects and assign them to variables.

Example:

let person = {
  name: "Alice",
  age: 30,
  getName: function() {
    return this.name;
  }
};

let { name, age, getName } = person;

console.log(name); // "Alice"
console.log(age); // 30
console.log(getName()); // "Alice"

Object.keys(), Object.values() and Object.entries() In Javascript:

`Object.keys()`, `Object.values()` and `Object.entries()`: Introduced in ES7 (ECMAScript 2017) and these functions allow developers to iterate over keys, values or both.

Example: Object.keys() method In Javascript

let person = {
  name: "Alice",
  age: 30,
  getName: function() {
    return this.name;
  }
};

let keys = Object.keys(person);
console.log(keys); // ["name", "age", "getName"]

Example: Object.values() method In Javascript

let person = {
  name: "Alice",
  age: 30,
  getName: function() {
    return this.name;
  }
};

let values = Object.values(person);
console.log(values); // ["Alice", 30, function]

Example: Object.entries() method In Javascript

let person = {
  name: "Alice",
  age: 30,
  getName: function() {
    return this.name;
  }
};

for( let [key, value] of Object.entries(person)) {
   console.log("key: ", key, "value: ", value);

  // key: "name" value: "Alice" // on iteration each line will print one by one.
  // key: "age" value: 30
  // key: "getName" value: function
}

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