Revised working demo growing bin packing

GrowingPacker = function(maxW, maxH) { this.maxW = maxW; this.maxH = maxH;};

GrowingPacker.prototype = {

  fit: function(blocks) {
    var n, node, block, len = blocks.length;
    var w = len > 0 ? blocks[0].w : 0;
    var h = len > 0 ? blocks[0].h : 0;
    this.root = { x: 0, y: 0, w: w, h: h };



    for (n = 0; n < len ; n++) {
      block = blocks[n];
      if (node = this.findNode(this.root, block.w, block.h)) {
        block.fit = this.splitNode(node, block.w, block.h);


      }

      else {
        block.fit = this.growNode(block.w, block.h);
      }
    }
  },

  findNode: function(root, w, h) {
    if (root.used)
      return this.findNode(root.right, w, h) || this.findNode(root.down, w, h);
    else if ((w <= root.w) && (h <= root.h))
      return root;
    else
      return null;
  },

  splitNode: function(node, w, h) {
    node.used = true;
    node.down  = { x: node.x,     y: node.y + h, w: node.w,     h: node.h - h };
    node.right = { x: node.x + w, y: node.y,     w: node.w - w, h: h          };
    return node;
  },

  growNode: function(w, h) {
    var canGrowRight  = (w <= this.root.w && this.root.w + w <= this.maxW);
    var canGrowDown = (h <= this.root.h && this.root.h + h <= this.maxH);

    if (canGrowRight) {
        return this.growRight(w, h);
    }
    else if (canGrowDown) {
        return this.growDown(w, h);
    }
    else

      return null; // need to ensure sensible root starting size to avoid this happening
  },

  growRight: function(w, h) {
    this.root = {
      used: true,
      x: 0,
      y: 0,
      w: this.root.w + w,
      h: this.root.h,
      down: this.root,
      right: { x: this.root.w, y: 0, w: w, h: this.root.h }
    };
    if (node = this.findNode(this.root, w, h))
      return this.splitNode(node, w, h);
    else
      return null;
  },

  growDown: function(w, h) {
    this.root = {
      used: true,
      x: 0,
      y: 0,
      w: this.root.w,
      h: this.root.h + h,
      down:  { x: 0, y: this.root.h, w: this.root.w, h: h },
      right: this.root
    };
    if (node = this.findNode(this.root, w, h))
      return this.splitNode(node, w, h);
    else
      return null;
  }

}

/*****************************************************************************************************/

var blocks = [
    { w: 500, h: 700 },
    { w: 500, h: 700 },
    { w: 500, h: 350 },
    { w: 500, h: 350 },
    { w: 500, h: 350 },
    { w: 500, h: 350 },
    { w: 500, h: 350 },
    { w: 500, h: 350 },
    { w: 500, h: 350 },
    { w: 500, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 },
    { w: 250, h: 350 }
];

var sheets = [];

while(blocks.length) {
    var packer = new GrowingPacker(1000,800);
    packer.fit(blocks);

    sheet = [];
    for (var i=blocks.length-1; i>=0; i--) {
        if (blocks[i].fit !== undefined && blocks[i].fit !== null) {
            //console.log(blocks[i].fit);
            sheet.unshift(blocks[i]);
            blocks.splice(i,1);
        }
    }
    //console.log(sheet[sheet.length-1].fit.y + sheet[sheet.length-1].h);
    //console.log(sheet);
    sheets.push(sheet);
}


for(var i=0; i<sheets.length; i++) {
    var sheet = sheets[i];
    var sheetWidth = sheet[sheet.length-1].w + sheet[sheet.length-1].fit.x;
    var sheetHeight = sheet[sheet.length-1].h + sheet[sheet.length-1].fit.y;

    for(var j=0; j<sheet.length; j++) {



    console.log("SHEET #" + i + " - W: " + sheetWidth + " H: " + sheetHeight + " BLOCK #" + j + " - W: " + sheet[j].w + " H: " + sheet[j].h + " X: " + sheet[j].fit.x + " Y: " + sheet[j].fit.y);
    }
}