Creating an awesome bar chart with d3.js

Following http://vegibit.com/create-a-bar-chart-with-d3-javascript/

HTML

<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/d3-selection-multi.v1.min.js"></script>
<div class="someclass">
  <div id="bar-chart">
  </div>
</div>

JavaScript

var chartdata = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120,
  135, 150, 165, 180, 200, 220, 240, 270, 300, 330, 370, 410
];

var margin = {
  top: 30,
  right: 10,
  bottom: 30,
  left: 50
}

var height = 400 - margin.top - margin.bottom,
  width = 720 - margin.left - margin.right,
  barWidth = 40,
  barOffset = 20;

var dynamicColor;

var yScale = d3.scaleLinear()
  .domain([0, d3.max(chartdata)])
  .range([0, height])

var xScale = d3.scaleBand()
  .domain(d3.range(0, chartdata.length))
  .range([0, width])

var colors = d3.scaleLinear()
  .domain([0, chartdata.length * .33, chartdata.length * .66, chartdata.length])
  .range(['#d6e9c6', '#bce8f1', '#faebcc', '#ebccd1'])

var awesome = d3.select('#bar-chart').append('svg')
  .attr('width', width + margin.left + margin.right)
  .attr('height', height + margin.top + margin.bottom)
  .style('background', '#bce8f1')
  .append('g')
  .attr('transform', 'translate(' + margin.left + ', ' + margin.top + ')')
  .selectAll('rect').data(chartdata)
  .enter().append('rect')
  .styles({
    'fill': function(data, i) {
      return colors(i);
    },
    'stroke': '#31708f',
    'stroke-width': '1'
  })
  .attr('width', xScale.bandwidth())
  .attr('x', function(data, i) {
    return xScale(i);
  })
  .attr('height', 0)
  .attr('y', height)
  .on('mouseover', function(data) {
    dynamicColor = this.style.fill;
    d3.select(this)
      .style('fill', '#3c763d')
  })

.on('mouseout', function(data) {
  d3.select(this)
    .style('fill', dynamicColor)
})

awesome.transition()
  .attr('height', function(data) {
    return yScale(data);
  })
  .attr('y', function(data) {
    return height - yScale(data);
  })
  .delay(function(data, i) {
    return i * 20;
  })
  .duration(2000)
  .ease(d3.easeElastic)

var verticalGuideScale = d3.scaleLinear()
  .domain([0, d3.max(chartdata)])
  .range([height, 0])

var vAxis = d3.axisLeft(verticalGuideScale)
  .ticks(10)

var verticalGuide =...