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| Mozilla [https://bugzilla.mozilla.org/show_bug.cgi?id=155749 doesn't support] the W3C's [http://www.w3.org/TR/DOM-Level-3-LS/load-save.html Document Object Model Load and Save] at this moment, so the easiest way to serialize and deserialize DOM trees is to use the following Mozilla-specific interfaces:
| | Moved [http://developer.mozilla.org/en/docs/Parsing_and_serializing_XML here] (MDC). |
| | | [[Category:Redirects]] |
| *[http://xulplanet.com/references/objref/XMLSerializer.html XMLSerializer] to serialize '''DOM trees to strings or to files'''
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| *[http://xulplanet.com/references/objref/DOMParser.html DOMParser] to parse XML from '''strings into DOM trees'''
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| *[http://xulplanet.com/references/objref/XMLHttpRequest.html XMLHttpRequest] to parse XML from '''files into DOM trees'''. Although <code>[http://xulplanet.com/references/objref/DOMParser.html DOMParser]</code> does have a method named <code>[http://xulplanet.com/references/objref/DOMParser.html#method_parseFromStream parseFromStream()]</code>, it's actually easier to [[XMLHttpRequest|use XMLHttpRequest]] which works for remote '''and''' local files.
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| ==Serializing DOM trees to strings==
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| First, create a DOM tree using code [[How to Create a DOM tree| like this]].
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| Now, let's serialize <code>doc</code> — the DOM tree — to a string:
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| <pre>
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| var serializer = new XMLSerializer();
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| var xml = serializer.serializeToString(doc);
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| </pre>
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| ==Serializing DOM trees to files==
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| First, create a DOM tree using code [[How to Create a DOM tree| like this]]. If you have already have a DOM tree from using [[XMLHttpRequest]], skip to the end of this section.
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| Now, let's serialize <code>doc</code> — the DOM tree — to a file (you can read more about using files in Mozilla [[Dev : Extensions : Example Code : File IO | here]]):
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| <pre>
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| var serializer = new XMLSerializer();
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| var foStream = Components.classes["@mozilla.org/network/file-output-stream;1"]
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| .createInstance(Components.interfaces.nsIFileOutputStream);
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| var file = Components.classes["@mozilla.org/file/directory_service;1"]
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| .getService(Components.interfaces.nsIProperties)
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| .get("ProfD", Components.interfaces.nsIFile); // get profile folder
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| file.append("extensions"); // extensions sub-directory
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| file.append("{5872365E-67D1-4AFD-9480-FD293BEBD20D}"); // GUID of your extension
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| file.append("myXMLFile.xml"); // filename
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| foStream.init(file, 0x02 | 0x08 | 0x20, 0664, 0); // write, create, truncate
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| serializer.serializeToStream(doc, foStream, ""); // rememeber, doc is the DOM tree
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| foStream.close();
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| </pre>
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| ==Serializing XMLHttpRequest objects to files==
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| If you have already have a DOM tree from using [[XMLHttpRequest]], use the same code as above but replace <code>serializer.serializeToStream(doc, foStream, "")</code> with <code>serializer.serializeToStream(xmlHttpRequest.responseText, foStream, "")</code> where <code>xmlHttpRequest</code> is an instance of [[XMLHttpRequest]].
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| ==Parsing strings into DOM trees==
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| <pre>
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| var theString='<a id="a"><b id="b">hey!</b></a>';
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| var parser = new DOMParser();
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| var dom = parser.parseFromString(theString, "text/xml");
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| // print the name of the root element or error message
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| dump(dom.documentElement.nodeName == "parsererror" ? "error while parsing" : dom.documentElement.nodeName);
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| </pre>
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| ==Parsing files into DOM trees==
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| ===XMLHttpRequest===
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| As was previously mentioned, even though <code>[http://xulplanet.com/references/objref/DOMParser.html DOMParser]</code> does have a method named <code>[http://xulplanet.com/references/objref/DOMParser.html#method_parseFromStream parseFromStream()]</code>, it's easier to use [[XMLHttpRequest]] to parse XML files into DOM trees ([[XMLHttpRequest]] works for both local and remote files). Here is sample code which reads and parses a local XML file into a DOM tree:
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| <pre>
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| var req = new XMLHttpRequest();
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| req.open("GET", "chrome://passwdmaker/content/people.xml", false);
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| req.send(null);
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| // print the name of the root element or error message
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| dump(dom.documentElement.nodeName == "parsererror" ? "error while parsing" : dom.documentElement.nodeName);
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| </pre>
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| <code>req.responseXML</code> is a <code>[http://xulplanet.com/references/objref/Document.html Document]</code> instance.
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| ===io.js===
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| If you prefer [[io.js]], this code will also parse a file into a DOM tree. Unlike [[XMLHttpRequest]], it will not work with remote files:
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| <pre>
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| var file = DirIO.get("ProfD"); // %Profile% dir
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| file.append("extensions");
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| file.append("{5872365E-67D1-4AFD-9480-FD293BEBD20D}");
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| file.append("people.xml");
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| var fileContents = FileIO.read(file);
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| var domParser = new DOMParser();
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| var doc = domParser.parseFromString(fileContents, "text/xml");
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| // print the name of the root element or error message
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| dump(dom.documentElement.nodeName == "parsererror" ? "error while parsing" : dom.documentElement.nodeName);
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| </pre>
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| [[Category:Example code]] [[Category:XML in Javascript]]
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