JavaScript is a versatile language mainly used for web development, enabling dynamic web pages through interaction with HTML and CSS. It includes features for manipulating the DOM, handling exceptions, validating user input, utilizing built-in objects, managing events, and working with JSON for data exchange. Key structures like try...catch for exception handling and methods for event listening exemplify JavaScript's capabilities.

1. Introduction to JavaScript
• JavaScript is a versatile language primarily
used for web development.
• It interacts with HTML and CSS to create
dynamic web pages.
• JavaScript is used for manipulating the DOM,
handling events, and more.
<script>
console.log("Hello, JavaScript!");
</script>

2. JavaScript DOM (Document Object
Model)
• DOM is a programming interface for HTML
and XML documents.
• It represents the structure of a document as a
tree of objects.
• JavaScript can be used to manipulate the DOM
to create interactive web pages.
document.getElementById("demo").innerHTML = "Hello DOM!";

3. Exception Handling in JavaScript
• Exception handling ensures that errors are
caught and managed properly.
• JavaScript provides the try...catch...finally
structure for handling exceptions.
try {
let x = 10;
let y = x + z; // z is undefined
} catch (error) {
console.log("Error: " + error.message);
}

4. JavaScript Validation
• JavaScript validation ensures that user input
meets the required format before submission.
• It is commonly used in forms to validate data.
function validateForm() {
let email = document.getElementById("email").value;
if (email === "") {
alert("Email is required.");
return false;
}
}

5. JavaScript Built-in Objects
• JavaScript has several built-in objects such as
Array, String, Date, and Math.
• These objects provide methods and properties
for common tasks.
let arr = [1, 2, 3];
console.log(arr.length); // Outputs: 3

6. JavaScript Event Handling
• Event handling allows JavaScript to react to
user actions such as clicks or keypresses.
• It is achieved through event listeners or event
handlers.
document.getElementById("btn").addEventListener("click",
function() {
alert("Button clicked!");
});

7. JSON in JavaScript
• JSON stands for JavaScript Object Notation
and is a lightweight format for data exchange.
• It is easy for both humans and machines to
read and write.
let person = {
"name": "John",
"age": 30,
"city": "New York"
};
let jsonString = JSON.stringify(person);
console.log(jsonString);