vertical bar showing the number of features for each dataset (each bar represents a dataset)

<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="utf-8">
		<title>Loading CSV Data with D3</title>
		<script type="text/javascript" src="https://d3js.org/d3.v3.min.js"></script>
	</head>
	<body>

var svg = d3.select("body")
						.append("svg")
						.attr("width", 1300)
						.attr("height", 400);
            
			//Load in contents of CSV file
			d3.csv("123 datasets.csv", function(data) {

rect=svg.selectAll("rect")
            .data(data)
            .enter()
            .append("rect")
            
            rect.attr("x",function(d,i){
                return i*10;
            })
            .attr("height",function(d){
                return d.nVars;
            })
            .attr("y",30)
            .attr("width",8)
            .attr("fill","green")
            .append("title")
            .text(function(d){
                return d.RelationName
            })
			});
            
            d3.select("body")
            .append("p")
            .text("Each bar corresponds to an experiment (scroll over for experiment title) and the height of the bar corresponds to the number of features being studied in that experiment")
		</script>

</body>
</html>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js