Turning nested JSON into an HTML nested list with Javascript

Question

I'm fairly new to using JSON (as opposed to XML) and am currently working purely with Javascript to digest, parse and display my returned JSON data.

I'm using the JSON2.js library and am getting back some valid JSON data representing a fairly simple nested list:

{
  "node":{
    "class":"folder",
    "title":"Test Framework",
    "node":{
      "class":"folder",
      "title":"Item 1",
      "node":{
        "class":"folder",
        "title":"Item 1.1",
        "node":{
          "class":"file",
          "title":"Item 1.1.a"
        }
      },
      "node":{
        "class":"folder",
        "title":"Item 1.2",
        "node":{
          "class":"file",
          "title":"Item 1.2.a"
        },
        "node":{
          "class":"file",
          "title":"Item 1.2.b"
        },
        "node":{
          "class":"file",
          "title":"Item 1.2.c"
        }
      },
      "node":{
        "class":"folder",
        "title":"Item 1.3",
        "node":{
          "class":"folder",
          "title":"Item 1.3.a",
          "node":{
            "class":"file",
            "title":"Item 1.3.a.i"
          },
          "node":{
            "class":"file",
            "title":"Item 1.3.a.ii"
          }
        }
      }
    },
    "node":{
      "class":"folder",
      "title":"Item 2",
      "node":{
        "class":"file",
        "title":"item 2.a"
      },
      "node":{
        "class":"file",
        "title":"Item 2.b"
      }
    }
  }
}

Does anyone have any pointers for a quick way to turn that lot into a UL with all of the nested elements? It would be cool as well if the "class" element that's in the JSON could be used as the class for each LI.

Any help is much appreciated.

Thanks,

Dave.

FWIW: I think there's something wrong with your JSON. There are a few places where you have multiple "node" keys in the same object. — Laurence Gonsalves
– Laurence Gonsalves, Commented Jul 31, 2009 at 10:36

2manyprojects · Accepted Answer · 2013-04-02 17:42:25Z

Your json is unsuited to your task. Some objects have several properties with the same name ("node"), so they are overriding one another. You have to use arrays of nodes instead. Here is a working data structure and the functions that can turn it into a nested list:

<!DOCTYPE HTML PUBLIC"-//W3C//DTD HTML 4.01//EN"
    "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title></title>
<script type="text/javascript">
function parseNodes(nodes) { // takes a nodes array and turns it into a <ol>
    var ol = document.createElement("OL");
    for(var i=0; i<nodes.length; i++) {
        ol.appendChild(parseNode(nodes[i]));
    }
    return ol;
}

function parseNode(node) { // takes a node object and turns it into a <li>
    var li = document.createElement("LI");
    li.innerHTML = node.title;
    li.className = node.class;
    if(node.nodes) li.appendChild(parseNodes(node.nodes));
    return li;
}

window.jsonData = [{
    "class": "folder",
    "title": "Test Framework",
    "nodes": [{
        "class": "folder",
        "title": "Item 1",
        "nodes": [{
            "class": "folder",
            "title": "Item 1.1",
            "nodes": [{
                "class": "file",
                "title": "Item 1.1.a"
            }]
        },
        {
            "class": "folder",
            "title": "Item 1.2",
            "nodes": [{
                "class": "file",
                "title": "Item 1.2.a"
            },
            {
                "class": "file",
                "title": "Item 1.2.b"
            },
            {
                "class": "file",
                "title": "Item 1.2.c"
            }]
        },
        {
            "class": "folder",
            "title": "Item 1.3",
            "nodes": [{
                "class": "folder",
                "title": "Item 1.3.a",
                "nodes": [{
                    "class": "file",
                    "title": "Item 1.3.a.i"
                },
                {
                    "class": "file",
                    "title": "Item 1.3.a.ii"
                }]
            }]
        }]
    },
    {
        "class": "folder",
        "title": "Item 2",
        "nodes": [{
            "class": "file",
            "title": "item 2.a"
        },
        {
            "class": "file",
            "title": "Item 2.b"
        }]
    }]
}];

</script>
</head>
<body>
    <input type="button" 
    onclick="document.body.appendChild(parseNodes(jsonData))"
    value="go" />
</body>
</html>

And I can add this css to have the items numberings match the node titles :)

<style type="text/css">
ol { list-style-type: none }
ol ol { list-style-type: decimal }
ol ol ol { list-style-type: decimal }
ol ol ol ol { list-style-type: lower-alpha }
ol ol ol ol ol { list-style-type: lower-roman }
</style>

See it in action.

Samir Talwar · Accepted Answer · 2009-07-31 10:43:34Z

Here's some fairly simple code that creates a <ul> element for each object, and a <li> element for each portion. You can add a quick check to test the child variable against things like "class" if you want to add a special case.

function jsonToHtmlList(json) {
    return objToHtmlList(JSON.parse(json));
}

function objToHtmlList(obj) {
    if (obj instanceof Array) {
        var ol = document.createElement('ol');
        for (var child in obj) {
            var li = document.createElement('li');
            li.appendChild(objToHtmlList(obj[child]));
            ol.appendChild(li);
        }
        return ol;
    }
    else if (obj instanceof Object && !(obj instanceof String)) {
        var ul = document.createElement('ul');
        for (var child in obj) {
            var li = document.createElement('li');
            li.appendChild(document.createTextNode(child + ": "));
            li.appendChild(objToHtmlList(obj[child]));
            ul.appendChild(li);
        }
        return ul;
    }
    else {
        return document.createTextNode(obj);
    }
}

This won't do exactly what you want, because your JSON doesn't make sense. Objects in JavaScript, and therefore JSON, are maps, and so you can't have more than one child with the same name. You'll need to turn your multiple "node"s into an array, as Cédric points out.

Blu · Accepted Answer · 2014-03-21 12:38:32Z

0

You can walk through your json structure by yourself and create appropriate <li> when needed, but I suggest you to implement Composite Pattern. See link for more details

edited Mar 21, 2014 at 12:38

Blu

4,0626 gold badges41 silver badges65 bronze badges

answered Jul 31, 2009 at 10:27

Pavel Podlipensky

8,2795 gold badges46 silver badges54 bronze badges

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