Access an XML node by value

Question

Is it possible to access an XML section / node using an attribute value (e.g. id) using JavaScript?

For example:

<people>
    <person id='1'>
        <name>Tom</name>
        <age>30</age>
    </person>
    <person id='2'>
        <name>Ian</name>
        <age>22</age>
    </person>
    <person id='3'>
        <name>Ben</name>
        <age>45</age>
    </person>
</people>

I want to be able to select a person with a given id. For example, finding the ID 2 would return Ian.

This is possible in ActionScript like so:

xml.people.person.(@id == 2).name

Is something similar available in JS?

The same thing works in JavaScript if you have E4X, which only Firefox has. So on the off chance that you're developing a Firefox extension... :) — Ry-
– Ry- ♦, Commented Jun 27, 2012 at 16:07
You may also want to look into jQuery.parseXML: api.jquery.com/jQuery.parseXML — ron tornambe
– ron tornambe, Commented Jun 27, 2012 at 16:47

Ry- · Accepted Answer · 2012-06-27 16:17:20Z

1

Assuming you have an XMLDocument, the only cross-browser way is to loop through the nodes:

var people = doc.getElementsByTagName('person');

for(var i = 0; i < people.length; i++) {
    if(people[i].getAttribute('id') === '2') {
        // Found it!
    }
}

If you need to do very complicated expressions, however, it may be worth it to use XPath, even though it needs a bit of cross-browser checking.

Here's the standard way:

document.evaluate('//person[@id='2']/text()[0]', doc.documentElement, null, XPathResult.STRING_TYPE, null).stringValue;

edited Jun 27, 2012 at 16:17

answered Jun 27, 2012 at 16:11

Ry-♦

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3 Comments

Donatas Olsevičius Over a year ago

It's a bad way to search for element, especially if the xml document is big. And it's not the only way, browsers do support XPath.

Ry- Over a year ago

@DonatasOlsevičius: I was in the process of adding XPath to my answer, but it's annoying in Internet Explorer, hence "the only cross-browser way".

Donatas Olsevičius Over a year ago

w3schools say it works in IE too, you just have to add some more code for it - w3schools.com/xpath/tryit.asp?filename=try_xpath_select_cdnodes However I cannot try it, I'm a Linux user.

nemo · Accepted Answer · 2012-06-27 16:34:21Z

1

var xml_text="<people><person id='1'><name>Tom</name><age>30</age></person><person id='2'><name>Ian</name><age>22</age></person><person id='3'><name>Ben</name><age>45</age></person></people>";

var xmlParser = new DOMParser().parseFromString(xml_text, "text/xml").documentElement;

var person2Name = xmlParser.querySelector("people person[id='2'] name").textContent ;

querySelector takes as input a string, which acts as a css selector on the node.

textContent gets the text of a node.

IE8 doesnt support DOMParser: but you can use the following workaround

  xmlParser =new ActiveXObject("Microsoft.XMLDOM");
  xmlParser.async=false;
  xmlParser.loadXML(xml_text);

edited Jun 27, 2012 at 16:34

answered Jun 27, 2012 at 16:11

nemo

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1 Comment

Ry- Over a year ago

+1, this is much better than XPath. Annoying Internet Explorer 8 doesn't support either DOMParser or easy XPath, though, even though it does support querySelector...

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