JSON vs XML parsing performance

Javascript October 1st, 2007

In one project I worked on is using XML format to pass data and handle them inside HTML web page with a MSXML parser object. I was thought if I pass the data in JSON format directly could be faster. However, after I wrote a simple test code to verify the idea, I found I was wrong.

I believe it’s because XML parsing is inside MSXML object and JSON parsing is using Jscript engine which have more overhead.

<html>
<head>
<title>JSON vs XML parse performance in browser</title>
<script>

function out(str)
{

var o = document.getElementById("output");

if (o!=null)
    o.innerHTML += str + "<br/>";

}

function generateJSON(size)
{
var strJSON = "[";
ch = ”;
for (i = 0 ; i < size; i++)
{
   strJSON += ch + ‘{"filename":"file’ + i + ‘.html"}’;
   ch = ‘,’;
}
strJSON += ‘]’;

return strJSON;
}

function generateXML(size)
{
var strXML = "<?xml version=’1.0′ encoding=’UTF-8′?>";

strXML += "<files>";

for ( i = 0 ; i < size; i++)
   strXML += "<file name=’file" + i + ".html’ ></file>";

strXML += "</files>";
return strXML;
}

function parseJSON(str)
{
data = eval(’(’ + str + ‘)’);
out(data.length + " data parsed");
}

function parseXML(str)
{
var xmlDoc = new ActiveXObject("Msxml2.DOMDocument");
xmlDoc.loadXML(str);

if (xmlDoc.documentElement!=null)
{
    var files = xmlDoc.documentElement.childNodes;
    out(files.length + " data parsed");
}
else
{
    out("Invalid XML parsed");
}
}

function testJSON()
{
var datasize = document.getElementById("datasize").value;
out("generating JSON for test…");

str = generateJSON(datasize);

out("begin parse JSON…");

var begin = new Date();
parseJSON(str);

var end = new Date();
out("Parse JSON data with " + datasize + " records, used time: " + (end - begin) + "ms");

}

function testXML()
{

var datasize = document.getElementById("datasize").value;

out("generating XML for test…");
var strXML = generateXML(datasize);

out("begin parse XML…");

var begin = new Date();
parseXML(strXML);

var end = new Date();
out("Parse XML data with " + datasize + " records, used time: " + (end - begin) + "ms");

}

</script>
<head>

<body>

Lines of data: <input type="edit" value="100" id="datasize"></input>
<input type="button" onclick="testJSON()" value="Test with JSON"></input>
<input type="button" onclick="testXML()" value="Test with XML"></input>

<hr/>

<div id="output">
</div>
</body>
</html>

Here is a result:

generating JSON for test…
begin parse JSON…
10000 data parsed
Parse JSON data with 10000 records, used time: 31ms
generating XML for test…
begin parse XML…
10000 data parsed
Parse XML data with 10000 records, used time: 16ms

generating JSON for test…
begin parse JSON…
20000 data parsed
Parse JSON data with 20000 records, used time: 78ms
generating XML for test…
begin parse XML…
20000 data parsed
Parse XML data with 20000 records, used time: 47ms

Feedback are welcome…

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2 Comments to “JSON vs XML parsing performance”

rockch | October 7th, 2007 at 8:42 am

I guess some reasons cause the result:
1. Javascript is a complex-syntax language and xml is simple-syntax text format. The javascript parsing will spend more overhead because it’s more complex than xml.
2. 20000 test cases will spend more time than 10000 test cases to allocate memory.
I guess JSON and parsing XML have little difference on performace if you test them under same amount test cases.
I think it’s the really reason that JSON has a nice-looking coding style and easy to use.
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