Why to study Web Technology ?

Learning Web Technology is crucial for engineering students because it equips them with essential skills to design and develop modern, user-friendly web applications. Understanding web technologies enables them to create interactive and responsive interfaces, integrate with back-end systems, and solve real-world problems. It also opens up diverse career opportunities in a rapidly growing industry, fostering innovation and adaptability in the ever-evolving digital landscape.

AJAX Practice

 Introduction to AJAX: Basics and Usage

AJAX (Asynchronous JavaScript and XML) is a set of web development techniques using various web technologies on the client side to create asynchronous web applications. With AJAX, web applications can send and retrieve data from a server asynchronously (in the background) without interfering with the display and behavior of the existing page.

 

Key Concepts of AJAX

1. Asynchronous Requests: AJAX allows you to send and receive data from a server asynchronously without refreshing the web page.

2. XMLHttpRequest Object: The core of AJAX is the `XMLHttpRequest` object, which facilitates communication with the server. It can handle data in various formats, including XML, JSON, HTML, and plain text.

3. jQuery and AJAX: jQuery provides methods that simplify the process of AJAX calls, making it easier to perform asynchronous operations with less code.

4. Callbacks and Promises: Handling the asynchronous results of AJAX calls can be managed using callbacks or promises, ensuring that certain code runs only after the AJAX request completes.

5. Handling Data: The data retrieved through AJAX can be used directly in the web page to update content dynamically, improve the user experience, and create responsive interfaces.

 

Examples and Discussion

Example 1: Basic AJAX Request using XMLHttpRequest

This example demonstrates how to create an AJAX request to load text data from a server.


```javascript

function loadDoc() {

  var xhttp = new XMLHttpRequest();

  xhttp.onreadystatechange = function() {

    if (this.readyState == 4 && this.status == 200) {

      document.getElementById("demo").innerHTML = this.responseText;

    }

  };

  xhttp.open("GET", "ajax_info.txt", true);

  xhttp.send();

}

```


```html

<button onclick="loadDoc()">Load Data</button>

<div id="demo"></div>

```

Example 2: AJAX with jQuery

Using jQuery to simplify the AJAX call to load JSON data from an API.


```javascript

$(document).ready(function(){

  $("#loadData").click(function(){

    $.ajax({

      url: "https://api.example.com/data",

      type: "GET",

      success: function(result){

        console.log(result);

        $("#demo").html(result.name);

      },

      error: function(error){

        console.log("Error: " + error);

      }

    });

  });

});

```


```html

<button id="loadData">Load Data</button>

<div id="demo"></div>

```

 

Example 3: Handling JSON Data

This example fetches JSON data and iterates over it to display specific elements on the webpage.


```javascript

function fetchData() {

  fetch('data.json')

    .then(response=> response.json())

    .then(data => {

      let output = '<ul>';

     data.forEach(function(user) {

        output += `<li>${user.name} - ${user.email}</li>`;

      });

      output += '</ul>';

      document.getElementById('users').innerHTML = output;

    })

    .catch(err => console.log(err));

}

```


```html

<button onclick="fetchData()">Fetch Data</button>

<div id="users"></div>

```

 Chapter Challenges

1. Real-Time Data Fetching: Create a feature that fetches weather data from a public API in real-time and updates the UI accordingly without refreshing the page.

2. Dynamic Search Feature: Implement a search box that retrieves search results from the server as the user types, displaying matching entries below the search box dynamically.

3. Form Submission without Refresh: Build a form that submits data to the server and displays a success message on the same page using AJAX, without reloading the page.

4. Content Management System: Develop a mini CMS where users can add, edit, and delete blog posts. Use AJAX to handle these operations asynchronously.

5. Pagination without Reloads: Implement pagination for a list of items fetched from the server where users can navigate through pages without reloading the page.

 

These AJAX exercises will help you understand how to effectively utilize AJAX in real-world applications, enhancing the interactivity and responsiveness of web applications.

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