📡 AJAX – Send GET Request: A Step-by-Step Guide with Examples

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🧲 Introduction – Why Use AJAX GET Requests?

AJAX GET requests are used to retrieve data from a server asynchronously—without reloading the entire page. Whether you’re fetching a list of users, loading articles, or populating a dropdown from an API, the GET method is your go-to solution when you don’t need to send data in the request body.

It’s lightweight, fast, and easy to implement using either the XMLHttpRequest object or the modern fetch() API.

🎯 In this guide, you’ll learn:

• How to send a GET request with AJAX
• Differences between GET and POST methods
• Real-world examples with code
• Best practices and debugging tips

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🔍 What Is an AJAX GET Request?

A GET request is an HTTP method used to request data from a specified resource. With AJAX, this can happen in the background—without interrupting the user experience.

Common use cases:

• Search suggestions
• Auto-complete fields
• Real-time data loading (e.g., weather, stock prices)
• Pagination and content loading

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🧱 AJAX GET Request Using XMLHttpRequest

✅ Example – Basic GET Request

var xhr = new XMLHttpRequest();
xhr.open("GET", "data.json", true); // true = asynchronous

xhr.onreadystatechange = function () {
  if (xhr.readyState === 4 && xhr.status === 200) {
    var data = JSON.parse(xhr.responseText);
    console.log("User:", data.username);
  }
};

xhr.send();

🔍 Explanation:

• xhr.open("GET", "data.json", true) → initializes the request
• xhr.onreadystatechange → monitors the request status
• xhr.readyState === 4 → means response is ready
• xhr.status === 200 → confirms success
• xhr.send() → sends the request

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🚀 AJAX GET Request Using Fetch API (Modern)

fetch("data.json")
  .then(response => {
    if (!response.ok) {
      throw new Error("HTTP error " + response.status);
    }
    return response.json();
  })
  .then(data => {
    console.log("User:", data.username);
  })
  .catch(error => {
    console.error("Error:", error);
  });

✅ This example achieves the same result using cleaner, promise-based syntax.

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🧪 Example – GET with Query Parameters

Suppose you want to search for a user by ID:

const userId = 5;
fetch("getUser.php?id=" + userId)
  .then(res => res.json())
  .then(data => console.log(data));

You can also encode parameters:

const query = new URLSearchParams({ id: 5, status: "active" });
fetch("getUser.php?" + query.toString())
  .then(res => res.json())
  .then(data => console.log(data));

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📊 GET vs POST in AJAX

Feature	GET	POST
Purpose	Retrieve data	Send data
Data in URL	Yes (in query string)	No (sent in request body)
Use case	Read operations	Form submission, uploads
Caching	Yes (by default)	No (unless manually handled)
Secure data	❌ Visible in URL	✅ Hidden in body

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⚠️ Common Mistakes to Avoid

❌ Mistake	✅ Fix
Not checking readyState & status	Always verify both before using response
Forgetting to handle errors	Use try/catch or .catch() with fetch()
Putting sensitive data in URL	Avoid sending passwords or tokens in GET
Not using encodeURIComponent()	Use it to encode dynamic URL parameters

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📌 Summary – Recap & Takeaways

AJAX GET requests are perfect for fetching data without reloading the page. Whether you’re using the traditional XMLHttpRequest or the modern fetch() API, the concept remains the same: request data, receive a response, and update the DOM dynamically.

🔍 Key Takeaways:

• Use GET for read-only operations
• Combine GET with query strings to pass data
• fetch() is recommended for modern JavaScript projects
• Handle errors and validate response status

⚙️ Next Steps:

• Create a live search field using AJAX GET
• Add loading spinners while waiting for a response
• Explore handling paginated API data using query parameters

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❓ FAQs – Sending AJAX GET Requests

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❓ When should I use a GET request instead of POST?
✅ Use GET when you want to retrieve data without altering anything on the server (e.g., load a profile, search, fetch a list).

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❓ Can I send form data using GET in AJAX?
✅ Yes, but it will be appended to the URL. Use POST for secure or large amounts of data.

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❓ Is GET secure for sending passwords or tokens?
❌ No. All data in a GET request is visible in the URL and browser history. Use POST with HTTPS instead.

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❓ Can I cache AJAX GET responses?
✅ Browsers may cache GET requests automatically. Use URL parameters like ?t=timestamp to prevent caching when needed.

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❓ How do I debug failed GET requests?
✅ Use browser dev tools → Network tab to inspect request/response headers, status codes, and errors.

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