Board Thread:Support Requests - Getting Technical/@comment-3147293-20150516125422

Actually I am writing a Javascript code to insert a statistical chart into the landing page. My intention is to show how much pages exist for each of major categories of the site, using an enhanced visual plugin.

I figured out that MediaWiki API provides information on categories: 

from http://ko.pokemon.wikia.com/api.php?action=query&format=json&prop=categoryinfo&titles=Category:NPC part is definitely what I am looking for. However, since I lack in API work experience, I didn't get arround to extract the data through AJAX and convert it to JavaScript variable.

Question: how can I get JSON-encoded data from server and pick up a specific key/value from it to convert to JS variable? 