10 Things To Know About JSON (JSON Javascript Examples)

I used JSON for the first time today and it’s really nothing special. I’ve heard about it a few times but never really given it much thought and theres no reason I should have. Here is the list of all you really need to know about this syntax for passing around name value pairs and arrays to javascript.

  1. JSON is an acronym for ‘Javascript Object Notation’.
  2. JSON is fast. Mostly because it is recognized natively by Javascript so there’s no processing overhead.
  3. JSON is an ordered list of name value pairs.
  4. JSON is so much easier to read and write than XML due to it’s simplicity.
  5. Apperently (Untested by me) data is formatted as JSON then Ajax can travel across domains.
  6. Almost every language used in web development either already has a JSON library or set of functions. If one doesn’t, then creating functions is a trivial task.
  7. ‘var jsonObject = { ‘cody : ‘taylor’ };’ is referenced by ‘jsonObject.cody’ which gives us ‘taylor’.
  8. ‘var jsonObect = {‘javascript’ : {‘json’ : ‘not xml’ };’ is referenced by ‘jsonObject.javascript.json’ which gives us ‘not xml’.
  9. You can also reference the JSON object as if it was an associative array like ‘jsonObject[‘cody’]’ or ‘jsonObject.javascript[‘json’]’ which gives the same values as previously.
  10. If you don’t want to use key/value pairs you can define a normal data array. ‘jsonObject = {‘arrayOfData’: {‘numbers’ : [‘1’, ‘2’, ‘3’]}};’ We use indexes for this dataset. Don’t use indexes for the collections defined in the ‘{ }’. ‘jsonObject.arrayOfData.numbers[1]’ will give us ‘2’.
  11. You can put functions in the dataset to pass around executable code.

So now you know basically all there is to know about JSON.

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4 Responses to “10 Things To Know About JSON (JSON Javascript Examples)”

  • Noah Says:
    June 3rd, 2009 at

    Please be aware that you should NOT put executable code into JSON objects and pass them to other runtimes using AJAX. That is how JSON injection occurs and most JSON libraries and implementations deter that behavior.

  • Noah Says:
    June 3rd, 2009 at

    But it is okay to use executable code in JSON within an application, in fact it is probably easier and more efficient than the way you are doing it now (assuming you’re not using JSON heavily).

  • Cody Taylor Says:
    June 3rd, 2009 at

    Thanks for the comment. Hmm JSON injection eh? Cross domain capabilities? Could be interesting.

  • Reedo Says:
    June 4th, 2009 at

    The 4th thing (ease of human reading/writing) is more a matter of preference. When there’s much nesting, I find XML easier to read than JSON (get ready to count those braces and brackets!). And while there are some excellent editors for XML, there are fewer out there for JSON.

    The 2nd thing (speed) is due more to the minimalist syntax than the Javascript compatibility, I believe. But the gain in network speed vs. XML isn’t as impressive when gzip-encoding the data, which everyone should be doing.