Detect if an Object has children in JavaScript

Question

In JavaScript you can get the children of an XML node like this...

var children = xml.childeNodes;

How do I get the children of an object?

var obj = {
  prop1: 'stuff',
  prop2: 'things',
  prop3: 'stuff-n-things'
}

---

Round two

Given an object like so..

var Obj = {
  levelOneProp1: 'stuff',
  levelOneProp2: 'things',
  levelOneProp3: {
     levelTwoProp1: 'moreStuff',
     levelTwoProp2: 'morethings',
     levelTwoProp3: 'morestuff-n-things'
  } 
}

I would like to know which properties in Obj have children so I can loop through them in a recursive manner. The goal is to be able to supply a dataset with an (theoretically) unlimited number of children and apply their values to input elements... Here is what I have so far.

function applyData( dataSet ){
    var hasChildren = false;

    for(var i = 0; i < dataSet.childNodeArrayGoesHere.length; i++){
        if(dataSet.detectChildNodesHere){
            hasChildren = true;
        }
    }

    if(hasChildren){
        for(var j = 0; j < dataSet.childNodeArrayGoesHere.length; i++){
            applyData(dataSet[j]);
        }
    } else {
        //apply the key/value pair to an input element

        $("input[name" + dataSet.propertyName + "]").val(dataSet.propertyValue);
    }
}

Answer 1

You can iterate over all properties of an object like this:

var o = { prop1: 'this is prop 1', prop2: 'this is prop2'};

for(var propName in o) {
    if(o.hasOwnProperty(propName)) {
        alert(o[propName]);   
    }
}

The hasOwnProperty() function checks to make sure that the specified property actually exists in the object. Using it in this context makes sure you don't get any inherited properties.