PWEB 3IA01 3IA02 | Pertemuan 3 | PJ Fierza

Summary

In this tutorial, the instructor introduces web development concepts, focusing on JavaScript, jQuery, and Ajax. The session covers variable declarations in JavaScript, including the differences between 'var', 'let', and 'const'. The instructor also explains operators, object-oriented programming (OOP), and how to create and manipulate objects using classes. Further, the session demonstrates the use of jQuery to simplify HTML manipulation, including dynamic interactions like adding paragraphs and list items through button clicks. The lesson concludes with an assignment, encouraging students to practice and apply these concepts in their projects.

Takeaways

• 😀 The session begins with an introduction to JavaScript, jQuery, and Ajax, following previous lessons on HTML and CSS.
• 😀 JavaScript variables can be declared using `var`, `let`, and `const`, with each having different scope and behavior.
• 😀 `var` has a global or function scope, meaning it can be redefined in different blocks, potentially causing issues in larger programs.
• 😀 `let` has a block-level scope, meaning it is confined to the block in which it is defined, preventing unwanted overwrites.
• 😀 `const` is used to define constants in JavaScript, and its value cannot be changed once set, unless it’s an object.
• 😀 JavaScript operators such as arithmetic, assignment, comparison, and modulo operators are used for various mathematical and logical operations.
• 😀 In Object-Oriented Programming (OOP), JavaScript allows the creation of classes and objects, with inheritance between parent and child classes.
• 😀 A class in JavaScript can be extended by child classes to inherit properties and methods from the parent class, e.g., a 'Car' class extending a 'Vehicle' class.
• 😀 Functions in JavaScript can be used to encapsulate reusable code, and the script demonstrates how to define and call functions.
• 😀 jQuery is introduced as a JavaScript library that simplifies HTML manipulation, event handling, and animations, making it easier to work with DOM elements.
• 😀 The session demonstrates practical examples using jQuery to manipulate HTML elements, such as adding paragraphs and list items through button clicks.
• 😀 The lesson concludes with a reminder to complete the activity and submit the assignment, including explanations on the importance of jQuery.

Q & A

What is the main focus of this meeting in web programming?

The main focus of this meeting is to introduce JavaScript, jQuery, and Ajax, including how to use them in web development.

What programming languages were discussed in the previous meetings?

In the previous meetings, the focus was on HTML and CSS.

What are the three types of variables in JavaScript discussed in the session?

The three types of variables in JavaScript discussed are var, let, and const.

How does the scope of variables differ between var, let, and const?

In JavaScript, 'var' has the widest scope and is not affected by blocks, while 'let' has block-level scope, and 'const' has block-level scope but its value cannot be reassigned, except when it’s an object.

What happens when you try to reassign a 'const' variable?

If you try to reassign a 'const' variable, it will result in an error, as 'const' variables are meant to hold constant values.

How does JavaScript handle variable scoping in an 'if' block?

JavaScript handles variable scoping such that variables declared with 'let' or 'const' inside an 'if' block are scoped to that block, while 'var' variables are accessible outside the block.

What is the purpose of using operators in JavaScript?

Operators in JavaScript are used to perform operations on variables, such as arithmetic, assignment, and comparison operations.

Can you explain the concept of Object-Oriented Programming (OOP) in JavaScript?

In JavaScript, Object-Oriented Programming (OOP) involves using classes to create objects, which have properties (attributes) and methods (behaviors). A class can inherit properties and methods from a parent class through 'extends'.

What is the significance of the 'extends' keyword in JavaScript?

'extends' is used in JavaScript to create a child class that inherits properties and methods from a parent class, allowing for code reuse and more structured object design.

What is jQuery and how does it help in JavaScript programming?

jQuery is a JavaScript library that simplifies HTML document manipulation, event handling, and animation. It makes working with JavaScript and HTML easier by providing convenient methods and syntax.

What is Ajax and why is it used in JavaScript?

Ajax (Asynchronous JavaScript and XML) is used to create dynamic and interactive web pages. It allows web pages to request and receive data from a server asynchronously without reloading the entire page.

How can jQuery be included in a project?

jQuery can be included in a project by using a CDN (Content Delivery Network) link or by downloading the jQuery file and linking it in the HTML file.

How does the example demonstrate the usage of jQuery in manipulating HTML elements?

In the example, jQuery is used to add event listeners to buttons. When button 1 is clicked, a new paragraph is added to the page, and when button 2 is clicked, a new list item is added to an ordered list.