JSONP

JSONP (JSON with Padding) is a technique used in web development to bypass the same-origin policy restrictions of web browsers, allowing data to be requested from a server in a different domain. It works by dynamically inserting a <script> tag into the HTML document, which loads a JavaScript file that contains JSON data wrapped in a callback function. This enables cross-domain data fetching in older browsers or environments where CORS (Cross-Origin Resource Sharing) is not supported.

Also known as: JSON with Padding, JSON-P, JSONP Callback, JSON Padding, JSONP Script Tag

Why learn JSONP?

Developers should learn JSONP when working with legacy systems or APIs that require cross-domain requests without CORS support, such as in older web applications or third-party services that only offer JSONP endpoints. It is particularly useful for fetching data from external APIs in scenarios where modern CORS headers cannot be implemented, though it has security risks like potential XSS vulnerabilities and should be used cautiously.

Learning Resources

• docs: MDN Web Docs: JSONP
• tutorial: W3Schools JSONP Tutorial
• video: JSONP Explained - YouTube Video
• docs: Stack Overflow: What is JSONP all about?