HTML unit 3-1

 Java-script:- 

HTML (Hypertext Markup Language) and JavaScript are two different technologies used for creating web pages and web applications.

HTML provides the structure and content of a web page, while JavaScript provides the interactivity and dynamic behavior. HTML uses markup tags to define different elements on a web page, such as headings, paragraphs, lists, and links, and allows you to add text, images, and other media.

JavaScript, on the other hand, is a programming language that runs in a web browser and allows you to create dynamic and interactive web pages. You can use JavaScript to manipulate the HTML document, handle user events, update the page content, and perform other tasks that make your web page interactive.

Together, HTML and JavaScript make it possible to create rich and engaging web experiences, from simple static pages to complex web applications.

DHTML :-

DHTML stands for Dynamic HTML and refers to the combination of HTML, Cascading Style Sheets (CSS), and JavaScript to create dynamic and interactive web pages. With DHTML, you can manipulate the appearance and behavior of a web page after it has been loaded in a browser, without having to refresh the entire page.

For example, you can use DHTML to hide and show elements on a page, change the layout and styling, animate elements, and handle user events such as clicks and hover events. You can also use DHTML to update the page content dynamically, either through user interactions or through background processes such as network requests.

DHTML was a popular technique in the early days of the web, and it paved the way for the more advanced web development techniques and frameworks we have today. However, with the advent of modern front-end frameworks such as Angular, React, and Vue, the use of DHTML has declined and is now considered a legacy technology.

Java-script 1.Basics,2.variables,3.string,4.math functions:- 

 1.Basics:-

JavaScript is a popular, high-level programming language that is used for creating dynamic and interactive web pages, building web applications, and creating desktop and mobile apps. Here are some of the basic concepts of JavaScript that you should know:

1. Variables: Variables are used to store data values in JavaScript. You can use variables to store numbers, strings, arrays, objects, and other data types.

2. Data Types: JavaScript has several data types, including number, string, boolean, and null. You can use the typeof operator to determine the data type of a variable.

3. Operators: JavaScript has several operators, such as arithmetic operators (+, -, *, /), comparison operators (==, !=, ===, !==), and logical operators (&&, ||).

4. Conditional Statements: You can use conditional statements, such as if/else, to control the flow of your program based on certain conditions.

5. Loops: Loops are used to repeat a block of code several times. JavaScript has two types of loops: for loops and while loops.

6. Functions: Functions are blocks of code that can be reused throughout your program. You can define a function and then call it as many times as you need.

7. Arrays: Arrays are data structures that allow you to store multiple values in a single variable. You can access individual elements in an array using their index.

8. Objects: Objects are complex data structures that allow you to store data in a more structured and organized manner. You can define properties and methods for an object.

These are just a few of the basic concepts of JavaScript, and there is much more to learn as you continue to develop your skills as a JavaScript programmer.

 2.variables:-

JavaScript variables are containers for storing data values. The variables in JavaScript can hold any data type such as strings, numbers, objects, arrays, and more.

Declaring a variable in JavaScript can be done using the "var" keyword (however, it's recommended to use "let" or "const" instead of "var" in modern JavaScript), followed by the variable name and an assignment operator (=) to store the value. 

In JavaScript, variables can be declared using the var, let, or const keywords. The difference between these keywords lies in the scope and mutability of the variables they declare.

The var keyword is used to declare a variable with function scope. This means that the variable is accessible within the function in which it is declared, as well as any nested functions.

The let keyword is used to declare a variable with block scope. This means that the variable is accessible only within the block in which it is declared, and not outside of it.

The const keyword is used to declare a constant, which is a variable that cannot be reassigned after it is declared.

It's recommended to use let and const instead of var in modern JavaScript. This is because let and const provide more control over the scope and mutability of variables, making it easier to write robust and maintainable code.

3.string:-

 

which types of java script outputs:-

In JavaScript, there are several ways to output the results of your code:

1. console.log() method: This method writes the output to the JavaScript console and is commonly used for debugging and testing purposes. For example:

console.log("Hello World!");
 

2. document.write() method: This method writes the output to the current web page. For example:

 <!DOCTYPE html>
<html>
<body>

<script>
document.write("Hello World!");
</script>

</body>
</html> 

3. innerHTML property: This property can be used to insert or modify the HTML content of an element. For example:

<!DOCTYPE html>
<html>
<body>

<p id="example">This is a paragraph.</p>

<script>
    document.getElementById("example").innerHTML = "Hello World!";
</script>

</body>
</html> 

4. alert() method: This method displays a message in a pop-up window. For example:

alert("Hello World!");  

5. document.querySelector() method: This method allows you to select and modify an element using CSS selectors. For example:

 <!DOCTYPE html>
<html>
<body>

<p class="example">This is a paragraph.</p>

<script>
    document.querySelector(".example").textContent = "Hello World!";
</script>

</body>
</html>
These are the most commonly used methods for outputting results in JavaScript. You can choose the method that best fits your specific needs and requirements.