D3 chart training

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    
    .axis text {
  font: 10px sans-serif;
}

.axis line,
.axis path {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}
  </style>
</head>

var yAxis = d3.svg.axis()
    .scale(y_scale)
    .orient("left");
    
    var svg = d3.select("body").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom)
    .attr("class", "axis")
    .style("background-color", "#aba")

var g = svg.append('g')
    .attr("transform", "translate("+margin.left+", "+margin.top+")")
    
    
   var xAxisG = svg.append('g')
    .attr("transform", "translate("+margin.left+", "+(height+margin.top)+")")
    .call(xAxis)
    
    
    var yAxisG = svg.append('g')
    .attr("transform", "translate("+margin.left+", "+margin.top+")")
    .call(yAxis)

var bars = g.selectAll('.fava').data(data);

bars.enter().append('rect')
    .attr({
      x:function(d, i){ return x_scale(d.x)},
      y: function(d, i){return y_scale(d.y)},
      fill:"yellow",
      width: x_scale.rangeBand(),
      height:function(d, i){return height - y_scale(d.y)}
    })

</script>
</body>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.js