Is parsing JSON faster than parsing XML

Question

I\'m creating a sophisticated JavaScript library for working with my company\'s server side framework.

The server side framework encodes its data to a simple XML for

Answer 1

In this situation, I'd say stick with the XML. All major browsers have a DOM parsing interface that will parse well-formed XML. This link shows a way to use the DOMParser interface in Webkit/Opera/Firefox, as well as the ActiveX DOM Object in IE: https://sites.google.com/a/van-steenbeek.net/archive/explorer_domparser_parsefromstring

Answer 2

JSON should be faster since it's JS Object Notation, which means it can be recognized natively by JavaScript. In PHP on the GET side of things, I will often do something like this:

<script type="text/javascript">
    var data = <?php json_encode($data)?>;
</script>

For more information on this, see here:

Why is Everyone Choosing JSON Over XML for jQuery?

Also...what "extra effort" do you really have to put into "generating" JSON? Surely you can't be saying that you'll be manually building the JSON string? Almost every modern server-side language has libraries that convert native variables into JSON strings. For example, PHP's core json_encode function converts an associative array like this:

$data = array('test'=>'val', 'foo'=>'bar');

into

{"test": "val", "foo": "bar"}

Which is simply a JavaScript object (since there are no associative arrays (strictly speaking) in JS).

Answer 3

If possible, it would make sense to just measure it. By 'if possible' I mean that tooling for javascript (esp. for performance analysis) may not be quite as good as for stand-alone programming languages.

Why measure? Because speculation based solely on properties of data formats is not very useful for performance analysis -- developers' intuitions are notoriously poor at predicting performance. In this case it just means that it all comes down to maturity of respective XML and JSON parser (and generators) in use. XML has the benefit of having been around longer; JSON is bit simpler to process. This based on having actually written libraries for processing both. In the end, if all things are equal (maturity and performance optimization of libraries), JSON can indeed be bit faster to process. But both can be very fast; or very slow with bad implementations.

However: I suspect that you should not worry all that much about performance, like many have already suggested. Both xml and json can be parsed efficiently, and with modern browsers, probably are. Chances are that if you have performance problems it is not with reading or writing of data but something else; and first step would be actually figuring out what the actual problem is.

Answer 4

Performance isn't really a consideration, assuming that you're not talking about gigabytes of XML. Yes, it will take longer (XML is more verbose), but it's not going to be something that the user will notice.

The real issue, in my opinion, is support for XML within JavaScript. E4X is nice, but it isn't supported by Microsoft. So you'll need to use a third-party library (such as JQuery) to parse the XML.

Answer 5

the difference in performace will be so tiny, you wouldn't even notice it (and: you shouldn't think about performance problems until you have performance problems - there are a lot of more important points to care for - maintainable, readable and documented code...).

but, to answer ayou question: JSON will be faster to parse (because it's simple javascript object notation).