What does the 'P' in JSONP stand for?

Question

I can't seem to find a definitive answer on this -- what does the p in JSONP stand for?. The candidates I've found so far are padding and prints. Anyone know where the JSONP name came from?

Answer 1

Padding.

from http://en.wikipedia.org/wiki/JSONP

JSONP or "JSON with padding" is a complement to the base JSON data format, a pattern of usage allowing a page to request data from a server in a different domain. JSONP is a solution to this problem, forming an alternative to a more recent method called Cross-Origin Resource Sharing. Padding

While the padding (prefix) is typically the name of a callback function that is defined within the execution context of the browser, it may also be a variable assignment, an if statement, or any other Javascript statement. The response to a JSONP request (namely, a request following the JSONP usage pattern) is not JSON and is not parsed as JSON; the returned payload can be any arbitrary JavaScript expression, and it does not need to include any JSON at all. But conventionally, it is a Javascript fragment that invokes a function call on some JSON-formatted data.

Said differently, the typical use of JSONP provides cross-domain access to an existing JSON API, by wrapping a JSON payload in a function call.

Hope that helped. Google wins!

Answer 2

Stone,

What I know, it stands for 'Padding'. There is a explaination about it on Wikipedia: JsonP

What it does?

It gives you the possibility to make a CROSS-DOMAIN request and get JSON data returned. Normally via the HTML script tag you call for another JavaScript.

But JsonP provide you a callback function and you can return noraml Json response.

Example:

You create a script tag:

• <script type="text/javascript" scr="http://anotherDomain/Car?CarId=5&jsonp=GiveCarResponse"></script>

In this script the GiveCarResponse is the callback function on the other Domain. Invoking this function will result in a Json response. In example:

{"CarId":5, "Brand":"BMVV", "GAS": false}

Does this make sense?

Answer 3

From wikipedia, it stands for "padding" (or with padding).

http://en.wikipedia.org/wiki/JSONP

Answer 4

Umm ... you've seen the wikipedia page, and you mistrust its accuracy?

This standards site seems to confirm the "with padding".

Answer 5

It basically means to add a calling function around JSON. AJAX can be called from your own server only and is not a cross domain. So to load data from different servers at client side, you make a JSONP request, basically you load a normal javascript file from other server just like you include a normal javascript file. Bust as JSON is not a valid javascript file, JSON is wrapped up in a function call to make it valid js file. the wrapped up function (already in your code) then extracts that data and show it on your page.