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Welcome to an in-depth exploration of AJAX and the Fetch API, two pivotal technologies that have transformed how web applications communicate with servers. In this lesson, we’ll delve into these concepts, providing practical examples and a real-world project related to 24/7 Teach, an online education platform.

Understanding AJAX

AJAX, which stands for Asynchronous JavaScript and XML, is a technique for creating fast and dynamic web pages. It allows web pages to update asynchronously by exchanging data with a web server behind the scenes. This means it's possible to update parts of a web page, without reloading the whole page.

How Does AJAX Work?

An event occurs in a web page (e.g., the page is loaded, a button is clicked)
An XMLHttpRequest object is created by JavaScript
The XMLHttpRequest object sends a request to a web server
The server processes the request
It sends a response back to the web page
The response is read by JavaScript
Proper action (like page update) is performed by JavaScript

AJAX with 24/7 Teach

Imagine you're using 24/7 Teach to browse through different courses. With AJAX, when you click on a course category, the course list can update dynamically without the need for a page refresh. This enhances user experience by providing quick and seamless interactions.

Introducing the Fetch API

The Fetch API provides a more powerful and flexible approach to asynchronous requests. It is a modern alternative to XMLHttpRequest and uses Promises, making it easier to work with and understand.

Basic Syntax of Fetch API

javascript

fetch(url) .then(response => response.json()) .then(data => console.log(data)) .catch(error => console.error('Error:', error));

Fetch API vs. XMLHttpRequest

Modern and Cleaner Syntax: Fetch uses Promises, making it more readable and organized.
Better Error Handling: Fetch distinguishes between network errors and server responses.
No Need for External Libraries: Fetch is built into the browser.

Using Fetch in 24/7 Teach

For a feature like fetching the details of a selected course, the Fetch API can be used. When a user selects a course, Fetch can request the course details from the server and dynamically display them without a page reload.

Practical Example: Fetching Data

Let's create a simple example to fetch and display a list of courses from 24/7 Teach.

HTML Setup

html

<div id="course-list"></div>

JavaScript Using Fetch API

javascript

fetch('https://api.247teach.org/courses') .then(response => response.json()) .then(courses => { const courseList = document.getElementById('course-list'); courses.forEach(course => { const courseElement = document.createElement('div'); courseElement.innerText = `Course Name: ${course.name}`; courseList.appendChild(courseElement); }); }) .catch(error => console.error('Error:', error));

In this example, we fetch a list of courses from 24/7 Teach’s API. For each course, we create a new div element, set its text, and append it to our course list container.

Error Handling in Fetch

A critical aspect of using Fetch is error handling. Unlike XMLHttpRequest, Fetch does not reject on HTTP error status. Instead, it resolves normally (with ok status set to false), and it only rejects on network failure or if anything prevented the request from completing.

javascript

fetch(url) .then(response => { if (!response.ok) { throw new Error('Network response was not ok'); } return response.json(); }) .then(data => console.log(data)) .catch(error => console.error('Error:', error));

This snippet demonstrates how to check for a successful response and how to handle exceptions properly.

Project Example: Interactive Course Enrollment

Now, let’s apply what we’ve learned to a real-world project. Imagine creating a feature on 24/7 Teach that allows users to enroll in courses interactively.

Project Overview

Objective: Build an interactive course enrollment feature.
Technology: HTML for structure, CSS for styling, and JavaScript with Fetch API for dynamic data handling.

Steps:

User Interface: Create a simple UI with a list of courses and an “Enroll” button next to each course.
Fetch Courses: Use Fetch API to retrieve the list of courses from 24/7 Teach’s API.
Enroll Feature: When a user clicks on “Enroll,” use Fetch to send a POST request to the server, enrolling the user in the course.

Example Code:

HTML:

html

<div id="courses-container"></div>

JavaScript:

javascript

In this scenario, each course has an “Enroll” button. When clicked, it triggers enrollInCourse(), which sends a POST request to enroll the user in the selected course.

Conclusion:

AJAX and the Fetch API are powerful tools in the modern web developer’s arsenal. They allow for the creation of responsive, dynamic, and user-friendly web applications. By integrating these technologies, you can enhance the functionality and interactivity of web applications like 24/7 Teach, improving the overall user experience.

It's time to test our understanding and engage in insightful discussions.

Lesson Questions: Please answer each question in your own words.

Name

First Name

Last Name

Email

Discuss the advantages and disadvantages of using Fetch API over the traditional AJAX with XMLHttpRequest. Consider aspects such as readability, error handling, and browser support. How do these differences impact the development of modern web applications?

What is the primary purpose of the Fetch API in web development?

a) To send data to the server synchronously

b) To update the entire web page upon receiving server data

c) To make asynchronous HTTP requests to the server for data d) To store data in the web browser's local storage

d) All of the above

Which of the following is true about error handling in Fetch API?

a) Fetch API uses the try-catch method for handling errors.

b) Fetch only rejects a promise when a network error occurs.

c) Fetch API automatically checks HTTP error status. d) Fetch API does not support error handling.

d) All of the above

Lesson Projects:

Project Assignment:

Add the URL/Link to your completed project in the space below.

http://

Real-World Project: Course Feedback System using Fetch API

Project Overview:

Develop a "Course Feedback System" for 24/7 Teach, where students can submit feedback for the courses they have enrolled in. The system should dynamically fetch course data and post user feedback to the server using Fetch API.

Objective:

To create an interactive system that enhances the user experience by enabling students to submit feedback without reloading the web page.

Technologies:

HTML for structuring the feedback form.
CSS for styling the form and feedback display.
JavaScript with Fetch API for handling asynchronous requests.

Steps:

Feedback Form Setup: Create an HTML form for submitting feedback. Include fields like courseId, studentName, feedback.
Fetching Courses: Use Fetch API to dynamically populate a dropdown with courses available for feedback.
Posting Feedback: When a user submits feedback, use Fetch API to send a POST request to the server with the feedback data.
Update UI: After submission, display a confirmation message without reloading the page.

Example Code

HTML:

html

<form id="feedbackForm"> <select id="courseDropdown"></select> <input type="text" id="studentName" placeholder="Your Name"> <textarea id="feedback" placeholder="Your Feedback"></textarea> <button type="submit">Submit Feedback</button> </form> <div id="confirmationMessage"></div>

JavaScript:

javascript

Project Execution:

This system enhances the user experience by providing real-time interactions and showcases the practical use of AJAX and Fetch API in handling forms and server communications in a modern web application.

Additional Project Resources:

Article 1: Using the Fetch API
Article 2: AJAX is Being Replaced

Submission Instructions:

Complete the Course Feedback application and integrate it into your existing 24/7 Teach project. Ensure the application is thoroughly tested and debugged.
Submit your project presentation above by EOD, 8 pm Wednesday. You'll receive feedback from your mentor to continuously improve your coding skills.

Evaluation Criteria:

Correct Implementation (40%)
- Successfully creates and configures an XMLHttpRequest object.
- Appropriately sets up the request using the open method with correct parameters (method, URL, asynchronous flag).
Response Handling (30%)
- Efficiently handles server responses in the onreadystatechange event handler.
- Correctly checks for readyState and status to ensure successful response processing.
- Implements meaningful processing or display of the server's response.
Error Handling (15%)
- Implements robust error handling, including network errors (using onerror) and HTTP error statuses.
Code Quality and Best Practices (10%)
- The code is well-organized, readable, and follows JavaScript best practices.
- Proper use of comments and naming conventions.
Functionality and Testing (5%)
- The AJAX request successfully retrieves and displays data, demonstrating full functionality.
- Evidence of thorough testing, ensuring reliability across various scenarios.

Participate in the Group Discussion:

Please answer the discussion question in the comment section below.

How do asynchronous operations like AJAX and Fetch contribute to the user experience in web applications? Discuss scenarios where asynchronous data fetching is essential and how it improves the performance and interactivity of web applications.

Lesson 17: AJAX and Fetch API - Revolutionizing Web Interactions