What is json format

Its filename extension for written programming code is. Here are important landmarks that form the history of JSON:. Performance — JSON is quite fast as it consumes very less memory space, which is especially suitable for large object graphs or systems. Dependency — JSON library does not require any other library for processing.

It can be used when key names are arbitrary strings. The given code example defines how to use JSON to store information related to programming books along with edition and author name. Here, JSON defines the first name, last name and id of a student.

While using W3Schools, you agree to have read and accepted our terms of use , cookie and privacy policy. Copyright by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3. A JSON string can be stored in its own file, which is basically just a text file with an extension of. You can include the same basic data types inside JSON as you can in a standard JavaScript object — strings, numbers, arrays, booleans, and other object literals.

This allows you to construct a data hierarchy, like so:. For example:. To access data further down the hierarchy, you have to chain the required property names and array indexes together. For example, to access the third superpower of the second hero listed in the members list, you'd do this:. Try loading this up and then accessing data inside the variable via your browser's JavaScript console. Below is also valid JSON, for example:.

The above is perfectly valid JSON. You'd just have to access array items in its parsed version by starting with an array index, for example [0]["powers"][0]. So, let's work through an example to show how we could make use of some JSON formatted data on a website. To begin with, make local copies of our heroes. We are going to load it into our page, and use some nifty DOM manipulation to display it, like this:. This is a very useful JavaScript object that allows us to make network requests to retrieve resources from a server via JavaScript e.

Meanwhile, the capability of making web requests in the background while a page was being shown, which had recently been introduced in Internet Explorer 5, was proving to be a viable approach to loading data incrementally for display. Instead of reloading the entire contents of the page, clicking the refresh button would trigger a web request that would load in the background.

When the contents were loaded, the data could be manipulated, saved, and displayed on the page using JavaScript, the universal programming language in browsers. JavaScript already had objects, which are a way of expressing data within the language, so Douglas Crockford took a subset of that expression as a specification for a new data interchange format and dubbed it JSON. JSON was much easier for people to read and for browsers to parse.

Today, JSON is the de-facto standard for exchanging data between web and mobile clients and back-end services. Below is a version of the data you saw above, this time in XML:. In addition to being more verbose exactly twice as verbose in this case , XML also introduces some ambiguity when parsing into a JavaScript-friendly data structure.

Converting XML to a JavaScript object can take from tens to hundreds of lines of code and ultimately requires customization based on the specific object being parsed. Although JSON is a relatively concise, flexible data format that is easy to work with in many programming languages, there are some drawbacks to the format.

Here are the five main limitations:. In the case of server-to-server communication, you might be better off using a serialization framework like Apache Avro or Apache Thrift.