A frequently emphasized advantage of XML is the availability of plenty tools to analyse, transform and selectively extract data out of XML documents. XPath is one of these powerful tools.

It's time to wonder, if there is a need for something like XPath4JSON and what are the problems it can solve.

Data may be interactively found and extracted out of JSON structures on the client without special scripting.

JSON data requested by the client can be reduced to the relevant parts on the server, such minimizing the bandwidth usage of the server response.

If we agree, that a tool for picking parts out of a JSON structure at hand does make sense, some questions come up. How should it do its job? How do JSONPath expressions look like?

Due to the fact, that JSON is a natural representation of data for the C family of programming languages, the chances are high, that the particular language has native syntax elements to access a JSON structure.

The following XPath expression

/store/book[1]/title

would look like

x.store.book[0].title

or

x['store']['book'][0]['title']

in Javascript, Python and PHP with a variable x holding the JSON structure. Here we observe, that the particular language usually has a fundamental XPath feature already built in.

The JSONPath tool in question should …