XML DOM

From http://www.w3schools.com (Copyright Refsnes Data)

# XML DOM

The DOM (Document Object Model) defines a standard way for accessing and manipulating documents.

## The XML DOM

The XML DOM (XML Document Object Model) defines a standard way for accessing and manipulating XML documents.

The DOM views XML documents as a tree-structure. All elements can be accessed through the DOM tree. Their content (text and attributes) can be modified or deleted, and new elements can be created. The elements, their text, and their attributes are all known as nodes.

In the examples below we use the following DOM reference to get the text from the <to> element:

xmlDoc.getElementsByTagName("to")[0].childNodes[0].nodeValue

- xmlDoc - the XML document created by the parser.
- getElementsByTagName("to")[0] - the first <to> element
- childNodes[0] - the first child of the <to> element (the text node)
- nodeValue - the value of the node (the text itself)

You can learn more about the XML DOM in our XML DOM tutorial.

## The HTML DOM

The HTML DOM (HTML Document Object Model) defines a standard way for accessing and manipulating HTML documents.

All HTML elements can be accessed through the HTML DOM.

In the examples below we use the following DOM reference to change the text of the HTML element where id="to":

document.getElementById("to").innerHTML=

- document - the HTML document
- getElementById("to") - the HTML element where id="to"
- innerHTML - the inner text of the HTML element

You can learn more about the HTML DOM in our HTML DOM tutorial.

## Parsing an XML File - A Cross browser Example

The following code loads an XML document ("note.xml") into the XML parser:

    <html>
    <head>
    <script type="text/javascript">
    function parseXML()
    {
    try //Internet Explorer
      {
      xmlDoc=new ActiveXObject("Microsoft.XMLDOM");
      }
    catch(e)
      {
      try //Firefox, Mozilla, Opera, etc.
        {
        xmlDoc=document.implementation.createDocument("","",null);
        }
      catch(e)
        {
        alert(e.message);
        return;
        }
      }
    xmlDoc.async=false;
    xmlDoc.load("note.xml");

    document.getElementById("to").innerHTML=
    xmlDoc.getElementsByTagName("to")[0].childNodes[0].nodeValue;
    document.getElementById("from").innerHTML=
    xmlDoc.getElementsByTagName("from")[0].childNodes[0].nodeValue;
    document.getElementById("message").innerHTML=
    xmlDoc.getElementsByTagName("body")[0].childNodes[0].nodeValue;
    }
    </script>
    </head>

    <body onload="parseXML()">
    <h1>W3Schools Internal Note</h1>
    <p><b>To:</b> <span id="to"></span><br />
    <b>From:</b> <span id="from"></span><br />
    <b>Message:</b> <span id="message"></span>
    </p>
    </body>
    </html>

Output:

# W3Schools Internal Note

To: Tove
From: Jani
Message: Don't forget me this weekend!

Try it yourself

## Important Note

To extract the text "Jani" from the XML, the syntax is:

    getElementsByTagName("from")[0].childNodes[0].nodeValue

In the XML example there is only one <from> tag, but you still have to specify the array index [0], because the XML parser method getElementsByTagName() returns an array of all <from> nodes.

## Parsing an XML String - A Cross browser Example

The following code loads and parses an XML string:

    <html>
    <head>
    <script type="text/javascript">
    function parseXML()
    {
    text="<note>";
    text=text+"<to>Tove</to>";
    text=text+"<from>Jani</from>";
    text=text+"<heading>Reminder</heading>";
    text=text+"<body>Don't forget me this weekend!</body>";
    text=text+"</note>";
    try //Internet Explorer
      {
      xmlDoc=new ActiveXObject("Microsoft.XMLDOM");
      xmlDoc.async="false";
      xmlDoc.loadXML(text);
      }
    catch(e)
      {
      try // Firefox, Mozilla, Opera, etc.
        {
        parser=new DOMParser();
        xmlDoc=parser.parseFromString(text,"text/xml");
        }
      catch(e)
        {
        alert(e.message);
        return;
        }
      }
    document.getElementById("to").innerHTML=
    xmlDoc.getElementsByTagName("to")[0].childNodes[0].nodeValue;
    document.getElementById("from").innerHTML=
    xmlDoc.getElementsByTagName("from")[0].childNodes[0].nodeValue;
    document.getElementById("message").innerHTML=
    xmlDoc.getElementsByTagName("body")[0].childNodes[0].nodeValue;
    }
    </script>
    </head>

    <body onload="parseXML()">
    <h1>W3Schools Internal Note</h1>
    <p><b>To:</b> <span id="to"></span><br />
    <b>From:</b> <span id="from"></span><br />
    <b>Message:</b> <span id="message"></span>
    </p>
    </body>
    </html>

Output:

# W3Schools Internal Note

To: Tove
From: Jani
Message: Don't forget me this weekend!

Try it yourself

Note: Internet Explorer uses the loadXML() method to parse an XML string, while other browsers uses the DOMParser object.

From http://www.w3schools.com (Copyright Refsnes Data)