As more and more Ajax-based applications raised up into web, something we have to concern is the size of data transfered between Server and Client.
From the name of Ajax, we know that data is transfered in XML format(asynchronized javascript and xml). But XML is too fat: the begin and end tag, quoted with '<>', element names which are used twice for each element. Although attributes can be used to cut fat away from xml documents, Large and complicated data can't be presented by attributes' value.
To these problem, Json format is becoming popular. It's small, easy to use, widely supported by most language.
A research shows that json takes valuable data at the percent of 60 , as xml does at only 25%.
John Resig has write an article about current state of json. In his article it is mentioned some popular json-apis has been used widely. but javascript level api is not enough, data is getting larger & larger, json-data parsing has became a time cost job, thus native json api is required.
simple best
