AJAX Applications

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AJAX Real-World Applications

By combining everything we have learned, we can build robust, highly interactive web applications.

AJAX is used extensively across the modern internet for various features you interact with daily.

Common AJAX Use Cases

Live Search: Showing dropdown suggestions as you type in a search bar.
Infinite Scrolling: Loading new images or posts automatically when you scroll to the bottom of a page.
Form Submission: Sending contact forms or login details without forcing a page reload.
Dynamic Data Tables: Sorting or filtering a table of products instantly.

Building an Interactive App

In a professional environment, an AJAX application combines HTML buttons, JavaScript event listeners, and backend APIs.

You request JSON or XML data, parse it, and completely manipulate the DOM elements on the screen.

Application Example:

function loadAppDashboard() {
  const xhttp = new XMLHttpRequest();
  xhttp.onload = function() {
    const data = JSON.parse(this.responseText);
    
// Building a complex application view dynamically
let html = "&lt;h3&gt;Welcome, " + data.username + "&lt;/h3&gt;";
html += "&lt;p&gt;You have " + data.messages + " unread messages.&lt;/p&gt;";

document.getElementById("dashboard").innerHTML = html;

  }
  xhttp.open("GET", "api/dashboard_data.json");
  xhttp.send();
}

<!DOCTYPE html>
<html>
<body>
  <h2>Interactive Dashboard App</h2>
  <button onclick="loadAppDashboard()" style="padding: 10px; font-size: 16px;">Load My Dashboard</button>
  <div id="dashboard" style="margin-top: 20px; padding: 20px; border: 2px solid #000; border-radius: 8px;">
    <p style="color: gray;">Dashboard is currently empty...</p>
  </div>
  
  <script>
    function loadAppDashboard() {
      const dashboard = document.getElementById("dashboard");
      dashboard.innerHTML = "Loading securely...";
      
      setTimeout(() => {
        const mockData = { username: "Akash", messages: 14 };
        let html = "<h3 style='color: blue; margin-top: 0;'>Welcome back, " + mockData.username + "!</h3>";
        html += "<p>You have <strong>" + mockData.messages + "</strong> unread messages.</p>";
        dashboard.innerHTML = html;
      }, 800);
    }
  </script>
</body>
</html>

Exercise 1 of 1

Which modern website feature relies heavily on the core concepts of AJAX?

Changing the background color using CSS stylesheets. Infinite scrolling (loading more content automatically at the bottom of a page).

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JS Basics

JS Syntax

JS Strings

JS Operators

JS Numbers

JS Control Flow

JS Functions

JS Objects

JS Dates

JS Arrays

JS Maps

JS Math

JS RegExp

JS Data Types

JSON Tutorial

AJAX Tutorial