The two are not the same thing. Therefore, one must always try to use Crockford's script that checks for a valid JSON before evaluating it. Link to the script explanation is found here and here is a direct link to the js file.
Every major browser nowadays has its own implementation for this. The JSON parser also offers another very useful method, stringify. This is useful for when you want to send data back to the server:. The above two methods parse and stringify also take a second parameter, which is a function that will be called for every key and value at every level of the final result, and each value will be replaced by result of your inputted function.
More on this here. Btw, for all of you out there who think JSON is just for JavaScript, check out this post that explains and confirms otherwise. Me: In prosaic English, the rules are pretty loose: just like with cage fighting.
Not so with JSON. There are many ways of describing something:. A computer is stupid and is not going to be able to understand sentences. So we gotta be really specific when computers are involved otherwise they get confused. Furthermore, JSON is a fairly efficient way of communicating, so most of the irrelevant stuff is cut out, which is pretty hand. If you wanted to communicate our family, to a computer, one way you could do so is like this:.
If you break those rules, then a computer simply will not understand i. A good way would be to use a json serialiser - which is a library which does the heavy lifting for you.
JSON is basically a way of communicating data to someone, with very, very specific rules. Using Key Value Pairs and Arrays. This is the concept explained, at this point it is worth reading the specific rules above. When executed with eval or otherwise , this code creates and returns a JavaScript object which contains the data you serialized. This is available because JavaScript allows the following syntax:.
You can use this for several purposes. For one, it's a comfortable way to pass data from your server backend to your JavaScript code. Thus, this is often used in AJAX. You can also use it as a standalone serialization mechanism, which is simpler and takes up less space than XML. Many libraries exists that allow you to serialize and deserialize objects in JSON for various programming languages.
In short, it is a scripting notation for passing data about. In some ways an alternative to XML, natively supporting basic data types, arrays and associative arrays name-value pairs, called Objects because that is what they represent. However it has become portable and is used in other languages too. The JSON format is often used for serializing and transmitting structured data over a network connection.
It is used primarily to transmit data between a server and web application, serving as an alternative to XML. It is a much-more compact way of transmitting sets of data across network connections as compared to XML.
You can accomplish the same effect with JSON and its mark-up is almost exclusively dedicated to the data itself and not the underlying structure. I like JSON mainly because it's so terse. For web content that can be gzipped, this isn't necessarily a big deal hence why x html is so popular. Get certified by completing a course today! If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail:.
Code for reading and generating JSON exists in many programming languages. You can receive pure text from a server and use it as a JavaScript object. Josh Fruhlinger contributed to this article. Jonathan Freeman is a software developer, consultant, and jazz musician living in Chicago. Through consulting, he's enjoyed working in various domains, from finance to healthcare to video games.
While he specializes in JavaScript, both browser and server side, he also takes a keen interest in modern data stores particularly graph databases and distributed computing platforms. Here are the latest Insider stories. More Insider Sign Out. Sign In Register. Sign Out Sign In Register. Latest Insider. Check out the latest Insider stories here.
More from the IDG Network. What is an API? Application programming interfaces explained. 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. This has led to more responsive web pages, and sounds exciting, but it is beyond the scope of this article to teach it in much more detail. Here we are storing the response to our request available in the response property in a variable called superHeroes ; this variable now contains the JavaScript object based on the JSON!
We have wrapped the code in an event handler that runs when the load event fires on the request object see onload — this is because the load event fires when the response has successfully returned; doing it this way guarantees that request. Now that we've retrieved the JSON data and converted it into a JavaScript object, let's make use of it by writing the two functions we referenced above.
First of all, add the following function definition below the previous code:. We then do a very similar operation with a paragraph: create it, set its text content and append it to the header. The only difference is that its text is set to a concatenated string containing both the homeTown and formed properties of the object.
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