XML Parser using JavaScript

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• To manipulate an XML document in javascript, you need an XML parser.

• Today all browsers come with in-built parsers that can parse the XML document.

• The parser loads the document into your computer’s memory. Once the document is loaded, its data can be manipulated using the DOM(Document Object Model).

• There is significant differences in implementation of Microsoft Browser based XML parser and the Mozilla browsers based XML parser.

XML Parser using JavaScript

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• Microsoft’s XML parser is a COM component that comes with Internet Explorer 5 and higher.

• To load the XML Parser in JavaScript will have to follow series of steps.

• Create instance of XML Parser:

<script type="text/javascript">

var xmlDoc=new ActiveXObject("Microsoft.XMLDOM");

</script>• This will load the xml parser in the memory and will wait for

the xml document. • This component will automatically get erased when you close

the browser window or the Browser. • Here the xmlDoc holds the XML Object for JavaScript.

XML Parser in Microsoft Browser

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• Synchronous load the XML Data

<script type="text/javascript">

xmlDoc.async="false";

</script>• This line turns off asynchronous loading, to make sure that

the parser will not continue execution of the script before the document is fully loaded.

XML Parser in Microsoft Browser

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Callback function

<script type="text/javascript">

xmlDoc.onreadystatechange = function name

</script>• Calls the callback function on change of every state while

loading the xml document.

XML Parser in Microsoft Browser

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XML Parser in Microsoft Browser

Ready States in Microsoft Browsers

1 Loading Preparing to read the XML file. Did not try yet

2 Loaded Parsing the XML file. Object model still not available

3 Interactive Part of XML file successfully parsed and read in. Object model partially available for read only

4 Completed Loading of the XML file has been completed, successfully or unsuccessfully

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• Load XML Document

<script type="text/javascript">

xmlDoc.load("abc.xml");

</script>

• Tells the parser to load abc.xml file.

XML Parser in Microsoft Browser