Making Graph in Javascript - Issue

I need some help debugging a problem with a simple graph (data structure, not a chart). I can insert a node, as well as create a path to the next nodes fine; that's not a problem. The problem is when I call returnGraph the node at the first index is returned as [object Object], but all the other nodes are returned as they should be. This is being wrriten with AngularJS by the way.

So I looked for a solution and I read in a few places that this has something to do with either the object's built in string method or a conflict between javascript-objects and json-objects. Unfortunately I'm a little lost since I'm not too familiar with Javascript internals.

First off, here is an example JSON object I am using:

//JSON object waiting to be passed to Node()
obj1 = {
    id: 6111,
    name: "Node1",
    stats: {
        "speed": 4
    },
    ranks: 5,
    prereq: 0
}

Here is the rest of the code:

//Pass data from the JSON object through the constructor to create a node
function Node(data){

    this.name = data.name;
    this.stats = data.stats;
    this.maxRank = data.ranks;
    this.rank = 0;
}

//Return node name
Node.prototype.returnName = function(){
    return this.name;
}

//Increase node rank
Node.prototype.increaseRank = function(){
    if (this.rank < this.maxRank){
        this.rank += 1;
    }
    console.log(this.rank);
}



//Graph object
function Graph(){
    this.edges = []
}

Graph.prototype.returnNeighbors = function(node){
    return this.edges[node];
}

Graph.prototype.addNeighbor = function(node1, node2, node3, node4){

    // Prints out node1 as an object
    console.log(node1); // Prints out node1 as an object
    if (node1 == null){
        console.log("something went terribly wrong!");
    }
    else if (node1 != null && node2 == null && node3 == null && node4 == null) {
        this.edges.push({[node1]: []});
    }
    else if (node4 == null){
        this.edges.push({[node1]:[node2, node3]})
    }
    else{
        this.edges.push({[node1]: [node2, node3, node4]})
    }
}

Graph.prototype.returnGraph = function(){
    return JSON.stringify(this.edges, null, 2);
}


// create a node for each JSON object
$scope.node1 = new Node(obj1);
$scope.node2 = new Node(obj2);
$scope.node3 = new Node(obj3);
$scope.node4 = new Node(obj4);


// create graph
var g = new Graph();
g.addNeighbor($scope.node1, $scope.node2, $scope.node3, $scope.node4);
$scope.g = g;

console.log(g.returnGraph());

This is where the problem lies and is what the above statement prints out. Keep in mind this is the Graph:

[
  {
    "[object Object]": [
      {
        "name": "Node2",
        "stats": {
          "speed": 4
        },
        "maxRank": 5,
        "rank": 0
      },
      {
        "name": "Node3",
        "stats": {
          "attack": 4
        },
        "maxRank": 5,
        "rank": 0
      },
      {
        "name": "Node4",
        "stats": {
          "block": 4
        },
        "maxRank": 5,
        "rank": 0
      }
    ]
  }
]

I've tried using JSON.parse() but that wasn't working. I also converted the first node into a string with JSON.stringify() and then directly input that string data instead of the actual object, which got me closer , yet it was full of escapes (\\,\t,\n). Using regex didn't help clean it up either.

So is there a better way to solve this [object Object] problem? I looked through a lot of answers but could not find a solution. Thanks for any help!