D3 chart help please

<%= @topic_view.topic.title %>
<%= @topic_view.topic.average_rating %> <%= @topic_view.topic.posts.count { |p| !!p.custom_fields['rating'] } %>

Why does this code cut off the first data set when graphing?

html code:

<body>
</body>

js/d3 code:

var dataSet = [10, 20, 30, 19, 9 
  ]

d3.select("body").selectAll("div")
.data(dataSet)
.enter()
.append("div")
.attr("class", "bar")
.style("height", (d)=> d + "px")

Your browser information:

User Agent is: Mozilla/5.0 (X11; CrOS x86_64 12239.67.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.102 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/data-visualization/data-visualization-projects/visualize-data-with-a-bar-chart