Parsing and serializing XML: Difference between revisions
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==Parsing files into DOM trees== | ==Parsing files into DOM trees== | ||
===XMLHttpRequest=== | |||
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 [[XMLHttpRequest|use XMLHttpRequest]]. That's what we'll demonstrate here. | 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 [[XMLHttpRequest|use XMLHttpRequest]]. That's what we'll demonstrate here. | ||
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dump(dom.documentElement.nodeName); | dump(dom.documentElement.nodeName); | ||
</pre> | </pre> | ||
===io.js=== | |||
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: | |||
<pre> | |||
var file = DirIO.get("ProfD"); // %Profile% dir | |||
file.append("extensions"); | |||
file.append("{5872365E-67D1-4AFD-9480-FD293BEBD20D}"); | |||
file.append("people.xml"); | |||
var fileContents = FileIO.read(sysBin); | |||
var domParser = new DOMParser(); | |||
domParser.parseFromString(fileContents); | |||
// print the name of the root element | |||
dump(dom.documentElement.nodeName); | |||
</pre> | |||
[[Category:Example code]] [[Category:XML in Javascript]] | [[Category:Example code]] [[Category:XML in Javascript]] |
Revision as of 22:38, 10 March 2005
Mozilla doesn't support the W3C's 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:
- XMLSerializer to serialize DOM trees to strings or to files
- DOMParser to parse XML from strings into DOM trees
- XMLHttpRequest to parse XML from files into DOM trees. Although
DOMParser
does have a method namedparseFromStream()
, it's actually easier to use XMLHttpRequest which works for remote and local files.
Serializing DOM trees to strings
First, create a DOM tree using code like this.
Now, let's serialize doc
— the DOM tree — to a string:
var serializer = new XMLSerializer(); var xml = serializer.serializeToString(doc);
Serializing DOM trees to files
First, create a DOM tree using code like this.
Now, let's serialize doc
— the DOM tree — to a file (you can read more about using files in Mozilla here):
var serializer = new XMLSerializer(); var foStream = Components.classes["@mozilla.org/network/file-output-stream;1"] .createInstance(Components.interfaces.nsIFileOutputStream); var file = Components.classes["@mozilla.org/file/directory_service;1"] .getService(Components.interfaces.nsIProperties) .get("ProfD", Components.interfaces.nsIFile); // get profile folder file.append("extensions"); // extensions sub-directory file.append("{5872365E-67D1-4AFD-9480-FD293BEBD20D}"); // GUID of your extension file.append("myXMLFile.xml"); // filename foStream.init(file, 0x02 | 0x08 | 0x20, 0664, 0); // write, create, truncate serializer.serializeToFile(doc, foStream, "IS0-8859-1"); // rememeber, doc is the DOM tree foStream.close();
Parsing strings into DOM trees
var theString='<a id="a"><b id="b">hey!</b></a>'; var parser = new DOMParser(); var dom = parser.parseFromString(theString, "text/xml"); // print the name of the root element dump(dom.documentElement.nodeName);
Parsing files into DOM trees
XMLHttpRequest
As was previously mentioned, even though DOMParser
does have a method named parseFromStream()
, it's easier to use XMLHttpRequest. That's what we'll demonstrate here.
First, read the local or remote XML file into a string:
var req = new XMLHttpRequest(); req.open("foo-bar!", "chrome://passwdmaker/content/people.xml", false); req.send(null);
The foo-bar
argument of XMLHttpRequest.open()
specifies the HTTP method to use if the URL (the second argument) is an HTTP(S) URL. Since we're using a chrome://
URL, the first argument to XMLHttpRequest.open()
is ignored. You should change this to GET/POST/PUT/DELETE/OPTIONS/TRACE/HEAD if using an HTTP(S) URL.
Now that we have the XML as a string (in req.responseText
), we can use the code similar to that in [#Parsing strings into DOM trees] to get the XML into a DOM tree:
var parser = new DOMParser(); var dom = parser.parseFromString(req.responseText, "text/xml"); // print the name of the root element dump(dom.documentElement.nodeName);
io.js
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:
var file = DirIO.get("ProfD"); // %Profile% dir file.append("extensions"); file.append("{5872365E-67D1-4AFD-9480-FD293BEBD20D}"); file.append("people.xml"); var fileContents = FileIO.read(sysBin); var domParser = new DOMParser(); domParser.parseFromString(fileContents); // print the name of the root element dump(dom.documentElement.nodeName);