I made a FIDDLE for you. I am storing a stack string and then output it, if the property is of primitive type:

function iterate(obj, stack) {
        for (var property in obj) {
            if (obj.hasOwnProperty(property)) {
                if (typeof obj[property] == "object") {
                    iterate(obj[property], stack + '.' + property);
                } else {
                    console.log(property + "   " + obj[property]);
                    $('#output').append($("<div/>").text(stack + '.' + property))
                }
            }
        }
    }

iterate(object, '')

Update: 17/01/2019

There used to be a different implementation, but it didn't work. See this answer for a prettier solution

So in your posted code, what happens is, if the source and target both contain the same key then nothing happens. The object is recursed down to the children. However if you simply change the inner block to this:

if (!target[key]) { 
  Object.assign(target, { [key]: {} });
}else{          
  target[key] = Object.assign({}, target[key])
}
mergeDeep(target[key], source[key]);

This will create a new assigned object for any key that is found in both the source and the target. Interestingly though, if you do this, your expected falseys will not show up in the console. This is because the target will always match the result, as it is the final mutated object. So in order to get your expected false results, you need to do something like the following:

var tester = source.params
const result = mergeDeep(source, b)
console.log(tester === result.params) // this will be false after the above addition

You can see your desired result here: http://jsbin.com/vicemiqiqu/1/edit?js,console

Your function seems a little odd. If I understood your question corectly, the answer maybe something like this

function recurse_object(obj) {

    var key='top';
    if (obj.hasOwnProperty(key)) {
       //here we change the y
       var keys = Object.keys(obj.top);
       var count='';
       var currentCount='';
       //go through all keys to find y because we don't know exact name
       for(var k in keys){
          if(k.indexOf('y')==0){
              currentCount=k.substring(1);
              if(currentCount!='')
                 count=parseInt(currentCount)+1;
              else 
                 count=1; 
          }
       }
       var x=obj;
       obj['y'+count]=obj.['y'+currentCount];
       delete obj.['y'+currentCount];
       obj.top=x;
    }
    else{
       obj.top=obj;
    }
 }

in object literal notation that you used to define object, avoid using this because this refers to window object. Instead you can used object name of which you are creating property like.

var obj = {
   testfunction: function() {
        obj.testfunction();
   }
};

You can use reduce() method and as accumulator pass object that you want add properties to.

var arr = ['one', 'two', 'three']
var obj = {}

arr.reduce(function(r, e, i) {
  r.path = e;
  return arr[i+1] ? r.nested = {} : r
}, obj)

console.log(obj)

If you want to use just recursion without loop you can create function like this.

var data = ['one', 'two', 'three']
var obj = {}

function makeObj(arr, n, o) {
  if (n == arr.length - 1) o.path = arr[n]
  else {
    o.path = arr[n];
    o.nested = {}
    makeObj(arr, n += 1, o.nested)
  }
  return o.nested
}

makeObj(data, 0, obj)
console.log(obj)

You could use a destructuring assignment for the wanted keys and use Array#map for getting a new array with only the one property and use Object.assign for the children objects by checking the children and if exist, take the urls from the children with a recursive call of the function.

function getUrls(array) {
    return array.map(({ url, children }) =>
        Object.assign({ url }, children && { children: getUrls(children) }));
}

var settings = [{ path: '/templates/pictures.php', url: '/pictures', label: 'Pictures', component: 'tab', template: 'default' }, { path: '/templates/post-article.php', url: '/user/:username', component: 'table', template: 'default', children: [{ path: '/templates/post-article-highlights.php', url: '/user/:username/highlights', component: 'table', template: 'default', children: [{ path: '/templates/post-article-highlights.php', url: '/user/:username/highlights', component: 'table', template: 'default' }] }] }],
    urls = getUrls(settings);

console.log(urls);

.as-console-wrapper { max-height: 100% !important; top: 0; }