AJAX Practice
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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>
```
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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