convert xml to json in Javascript

Question

I have the following javascript function (which I got from Stack Overflow) which converts XML to JSON:

function xmlToJson(xml) {
    try {
        var obj = {};
        if (xml.nodeType == 1) {
            if (xml.attributes.length > 0) {
                for (var j = 0; j < xml.attributes.length; j++) {
                    var attribute = xml.attributes.item(j);

                    obj[attribute.nodeName] = attribute.nodeValue;
                }
            }
        } else if (xml.nodeType == 3) {
            obj = xml.nodeValue;
        }

        if (xml.hasChildNodes()) {
            for (var i = 0; i < xml.childNodes.length; i++) {
                var item = xml.childNodes.item(i);
                var nodeName = item.nodeName;

                if (typeof (obj[nodeName]) == "undefined") {
                    obj[nodeName] = xmlToJson(item);
                } else {
                    if (typeof (obj[nodeName].push) == "undefined") {
                        var old = obj[nodeName];

                        obj[nodeName] = [];
                        obj[nodeName].push(old);
                    }

                    obj[nodeName].push(xmlToJson(item));
                }
            }
        }

        console.log(JSON.stringify(obj));
        return obj;
    } catch (e) {
        alert(e.message);
    }
}

What I want is to return it as an array ([]) when a xml node has at-least single child node and it has a parent node also. In this code it returns map ({}) if xml node has single child node but it is fine with multiple child nodes.

For example, I'd like the XML

<pnode attr1="abc">
    <cnode attr2="xyz"></cnode>
</pnode>

to be transformed into the JSON

{
    "pnode": {
        "attr1": "abc"
    },
    "cnode": [
        {"attr2": "xyz"}
    ]
}

I hate to ask the obvious, but "What have you tried?"... and "What didn't work?" — Steve
– Steve, Commented Sep 27, 2013 at 16:17
JSON is great, but what's wrong with XML? Work with the dataformat you have, don't convert it for no apparent good reason at all ! — adeneo
– adeneo, Commented Sep 27, 2013 at 16:19
if my xml is like xml='<pnaode attr1="abc"><cnode attr2="xyz"></cnode></pnode>' then I want json like {"pnode":{"attr1":"abc"},"cnode":[{"attr2":"xyz"}]} — Anand Jha
– Anand Jha, Commented Sep 27, 2013 at 16:32

Paul S. · Accepted Answer · 2013-09-27 18:05:09Z

With the clarification about what you want to achieve, here is an algorithm. I'll leave my other answer up because I still think the wisest choice is not to play with the structure

function flattenNodes(node, isChild) {
    var obj = {}, obj2, i, key, attributes = {};
    if (node.attributes && node.attributes.length)
        for (i = 0; i < node.attributes.length; ++i)
            attributes[node.attributes[i].nodeName] = node.attributes[i].nodeValue;
    if (!isChild)
        obj[node.nodeName] = attributes;
    else {
        if (!obj.hasOwnProperty(node.nodeName))
            obj[node.nodeName] = [];
        else if (!(obj[node.nodeName] instanceof Array))
            obj[node.nodeName] = [obj[node.nodeName]];
        obj[node.nodeName].push(attributes);
    }
    attributes = null; // free
    if (node.childNodes && node.childNodes.length)
        for (i = 0; i < node.childNodes.length; ++i) {
            if (node.childNodes[i].nodeType === 3) continue; // skip text node
            obj2 = flattenNodes(node.childNodes[i], 1); // recurse
            for (key in obj2) // merge
                if (obj2.hasOwnProperty(key))
                    if (!obj.hasOwnProperty(key)) {
                        obj[key] = obj2[key];
                    } else {
                        if (!(obj[key] instanceof Array))
                            obj[key] = [obj[key]];
                        obj[key] = obj[key].concat(obj2[key]);
                    }
        }
    return obj;
}

Example usage on Node root_node

var root_node;
root_node = new DOMParser().parseFromString(
    '<pnode attr1="abc"><cnode attr2="xyz"></cnode></pnode>',
    'text/xml'
).documentElement;

var o = flattenNodes(root_node); // create
JSON.stringify(o);               // to JSON
// {"pnode":{"attr1":"abc"},"cnode":[{"attr2":"xyz"}]}

If you have XML of the form <foo bar="baz"><foo hello="world"></foo></foo>, the first iteration will cause {foo: {bar: "baz"}}, then the second encounter will modify this to the array form of {foo: [{bar: "baz"}, {hello: "world"}]}

Paul S. · Accepted Answer · 2013-09-27 16:32:41Z

0

I would form the object representing the XML differently;

Integer  nodeType
String   nodeName
String   nodeValue
Array    childNodes
Object   attributes

Now you can have the same form independent of number of child nodes/etc

function nodeToObject(node) {
    var obj = {}, i;
    obj.nodeType = node.nodeType;
    obj.nodeName = node.nodeName;
    obj.nodeValue = node.nodeValue;
    obj.childNodes = [];
    obj.attributes = {};
    if (node.childNodes && node.childNodes.length)
        for (i = 0; i < node.childNodes.length; ++i)
            obj.childNodes.push(nodeToObject(node.childNodes[i]));
    if (node.attributes && node.attributes.length)
        for (i = 0; i < node.attributes.length; ++i)
            obj.attributes[node.attributes[i].nodeName] = node.attributes[i].nodeValue;
    return obj;
}

And then to transform root_node to JSON,

JSON.stringify(nodeToObject(root_node));

Going in the opposite direction is also possible in JavaScript, with some minor logic based upon nodeType to choose the creation method.

answered Sep 27, 2013 at 16:32

Paul S.

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5 Comments

Paul S. Over a year ago

Just pointing out in case it is not clear; the biggest difference here is I use a single Array called childNodes, not many Arrays for each different nodeName. I also keep the nodeName

Anand Jha Over a year ago

Thanks Paul, but this it not what I am looking for, i don't want to add extra attribute. if my xml is like xml='<pnaode attr1="abc"><cnode attr2="xyz"></cnode></pnode>' then I want json like {"pnode":{"attr1":"abc"},"cnode":[{"attr2":"xyz"}]} but it is coming like {"pnode":{"attr1":"abc"},"cnode":{"attr2":"xyz"}}

Paul S. Over a year ago

I edited your question to show this you just commented, but I don't understand the full behaviour you desire by how you've explained it - what do you want to happen if there are several nodes of the same name, what do you want to happen if they have different attribute names, what do you want to happen if they have the same attribute name, and why does <pnode> not an Array when <cnode> is?

Anand Jha Over a year ago

Thanks Paul for making my question more understandable. I want Array for only those nodes who have a parent node too. in this case <pnode> has no any parent node but <cnode> does.

Paul S. Over a year ago

@anand4tech what happens if you have <foo bar="baz"><foo hello="world"></foo></foo> ? (i.e. both with same name, only one has a parent). Also please consider editing your question to include this information too. You should also link to the original source of the code you have already if you didn't write it yourself, especially as it is a whole algorithm.

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