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JavaScript AJAX Basics (retiring) AJAX and APIs Displaying the Photos

Konstantinos Pedarakis
Konstantinos Pedarakis
21,301 Points
Posted by Konstantinos Pedarakis
Konstantinos Pedarakis
21,301 Points

what is the jsoncallback=? part of the query string?

Ok! i've manage to complete all the steps and pretty much it was easy for me to understad cause im not new in programming in general, but because im not involved very much with API's that part at the end of the url confused me. what is that jsoncallback part of the query string and where do we use it? why do we use it? we use it every time? and why? Thanks for any clarification.

1 Answer

Arturo Alviar
Arturo Alviar
15,739 Points
Arturo Alviar
Arturo Alviar
15,739 Points

Hi Konstantinos,
The jsoncallback=? part of a query is a special parameter that requests JSONP (JSON with Padding). When doing an AJAX request, you are restricted by the "Same-origin" policy meaning that whatever you request must be in the same domain from where the request was made. With this parameter, the query does not perform a regular AJAX request.

With JSONP, we can get around the "Same-origin" policy and successfully obtain data from a different origin (i.e. a different website).

Hope this helps!

Konstantinos Pedarakis
Konstantinos Pedarakis
21,301 Points
Konstantinos Pedarakis
Konstantinos Pedarakis
21,301 Points

Hi Arturo Alviar , Thanks for taking the time to reply. Yes, this makes more sense now. Another question that just came up, this jasoncallback=? part or the query string is the same everytime that i want to make a JSONP request? i mean is a standard part of the string when i am about to get around the "Same-origin" policy? And is everywhere the same? i mean if i was making some requests, not to flickr lets say, but to Facebook or Twitter, the jsoncallback=? would be the same there as well? Thanks.

Arturo Alviar
Arturo Alviar
15,739 Points
Arturo Alviar
Arturo Alviar
15,739 Points

Hi Konstantinos,

Generally the JSONP parameter is callback=? but it can vary depending on the server-side API (although usually the convention is callback=?).

With Facebook and Twitter, making JSONP requests can be done using the callback=? parameter.