JS Tutorial


JS OBJECT PROPERTIES



JavaScript Object Properties

In JavaScript, an object is a standalone entity, with properties and methods. An object property is a key-value pair, where the key is a string (also called a property name) and the value can be any data type, such as strings, numbers, arrays, and even functions.

🔹 Key Concepts of Object Properties:
  • Property Name (Key) – The name of the property (also called the key) of an object
  • Property Value – The value associated with a property, which can be any valid JavaScript data type (string, number, array, function, etc.)
  • Dot Notation – A way of accessing object properties using a dot (e.g., object.property)
  • Bracket Notation – A way of accessing object properties using square brackets (e.g., object['property'])

📌 Defining Object Properties

In JavaScript, we can define an object using the following syntax:

Syntax:

const objectName = {
  propertyName1: value1,
  propertyName2: value2,
  // more properties
};

Here, objectName is the object, and propertyName1, propertyName2, etc., are its properties. The values associated with each property can be of any type.

📌 Accessing Object Properties

You can access an object’s properties using two main techniques:

1. Dot Notation

Dot notation is the most common way to access a property of an object.

Syntax:

object.propertyName;

Example:

const person = { name: "Alice", age: 25 };
console.log(person.name); // Output: Alice

2. Bracket Notation

Bracket notation allows you to access object properties with a string key, and it’s useful when the property name contains special characters or spaces.

Syntax:

object["propertyName"];

Example:

const person = { name: "Alice", age: 25 };
console.log(person["name"]); // Output: Alice

📌 Modifying Object Properties

You can modify the properties of an object by simply reassigning a new value to an existing property.

Syntax:

object.propertyName = newValue;

Example:

const person = { name: "Alice", age: 25 };
person.age = 26;
console.log(person.age); // Output: 26

📌 Deleting Object Properties

To remove a property from an object, you can use the delete operator.

Syntax:

delete object.propertyName;

Example:

const person = { name: "Alice", age: 25 };
delete person.age;
console.log(person.age); // Output: undefined

📌 Adding New Properties to an Object

You can easily add new properties to an object using dot notation or bracket notation.

Syntax:

object.newProperty = value; // Using dot notation
object["newProperty"] = value; // Using bracket notation

Example:

const person = { name: "Alice", age: 25 };
person.city = "New York";
console.log(person.city); // Output: New York

📌 Summary of JavaScript Object Property Operations:

  • Objects in JavaScript are collections of key-value pairs, where the key is a string (property name) and the value can be any data type.
  • You can access properties using dot notation or bracket notation.
  • Properties can be modified, deleted, or added using different techniques.
  • JavaScript objects are dynamic, meaning you can change their properties during runtime.

📌 Practice Exercise: Modify the Object Properties

Try modifying the object below by changing its properties:


Your result will appear here

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