new enter in groups

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <script>
    
    data = d3.range(5)
    // Feel free to change or delete any of the code you see in this editor!
    var svg = d3.select("body").append("svg")
      .attr("width", 960)
      .attr("height", 500)

function redraw(size) {
    var selection = svg.selectAll(".nodes").data(data)
    
    enterSelection = selection.enter().append("g")
    								.attr("class", "nodes")
    
    enterSelection.append("rect")
      .attr("height", size)
      .attr("width", size)
    		.attr("x", function(d) {return 200+ d*10})
    		.attr("y", function(d) {return 100+ d*10})
    		.attr("fill", "black")
    
    enterSelection.append("circle")
    		.attr("r", size)
    		.attr("cx", function(d) {return 100+ d*10})
    		.attr("cy", function(d) {return 100+ d*10})
    		.attr("fill", "black")
    
    //How to update?
    enterSelection.merge(selection)
      	.select("circle")
      .transition()
      .duration(1000)
      .delay(function(i) {return i*100})
    		.attr("r", size)
    		.attr("cx", function(d) {return 100+ d*10})
    		.attr("cy", function(d) {return 100+ d*10})
    		.attr("fill", "black")
    	
    
    
    
    }
    
    redraw(10)
    
    data = d3.range(10)
    
    redraw(20)

</script>
</body>

https://d3js.org/d3.v4.min.js