duplicate move

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    svg { width:100%; height: 100% }
    .mbutton {stroke: #c4c4c4; fill: #f4f4f4; stroke-width: 2px;}
    .dumtex {stroke: none; fill: #111222; font-size: 1em;}
  </style>
</head>

<body>
  <script>
    function translate(x, y){
        return "translate(" + [x, y] + ")"  
    }
    
    var lh = 14;  // line height    
    var img_prefix = "https://cloud.githubusercontent.com/assets/"
    var img_bottom = "619340/15272843/64e20f62-1a86-11e6-8b90-054116da90fa.png"
    var img_top = "619340/15272846/6ac53e72-1a86-11e6-806a-f32b4017068b.png"
    
    var svg = d3.select("body").append("svg")
    
    function make_image(image_name, url, op){
        var obj = svg.append("image")
            .classed(image_name, true)
            .attr({x: 100, y: 10, height: 500, width: 500})
            .attr({"xlink:href": url, opacity: op})
        return obj
    }

button1.on('click', function(){
      mover(4*-lh)
    })

button2.on('click', function(){
         var img = d3.select('.top_image_2')
             .transition()
             .duration(9)
             .attr({opacity: 1.0})
         mover(5*-lh)
    })
    
    button3.on('click', function(){
         d3.select('.top_image_2').attr({opacity: 0.0, transform: translate(0,0)})
         d3.select('.top_image').attr({transform: translate(0,0)})
             
    })

</script>
</body>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js