Simple bar chart

This is an example of a simple bar chart. Most beginners to d3 will build one of these charts at some point.

See http://www.puzzlr.org/?p=25 for the thought process behind this graph.

<!DOCTYPE html>
<meta charset="utf-8">
<html>
<head>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="https://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"></script>
<style>
body {
 font: 16px sans-serif;
font-weight: bold;	
}

.bar {
  fill: steelblue;
}

.bar:hover {
  fill: purple;
}

.axis {
  font: 10px sans-serif;
}

.axis path, /* path refers to a line */
.axis line {
  fill: none;	
  stroke: #000;
  shape-rendering: crispEdges;
}

.x.axis path {
  display: none; 
}
.title {
	font: 20px sans-serif;
	font-weight: bold;
}

/* tooltip CSS */

.d3-tip {
  line-height: 1;
  font-weight: bold;
  padding: 12px;
  background: rgba(0, 0, 0, 0.8);
  color: #fff;
  border-radius: 2px;
}

.d3-tip:after {
  box-sizing: border-box;
  display: inline;
  font-size: 10px;
  width: 100%;
  line-height: 1;
  color: rgba(0, 0, 0, 0.8);
  content: "\25BC";
  position: absolute;
  text-align: center;
}

/* Style northward tooltips differently */
.d3-tip.n:after {
  margin: -1px 0 0 0;
  top: 100%;
  left: 0;
}
</style>
</head>
<body>
<script> 
var margin = { 
	top: 30,
	left: 65,
	right: 20,
	bottom: 50
}
height = 400 - margin.top - margin.bottom
width = 600 - margin.left - margin.right

svg.call(tip);

d3.csv("internet_users.csv",type,  function(data) { 
	xScale.domain(data.map(function(d) {return d.Year;})); 
	yScale.domain([0, d3.max(data, function(d) { return +d["Internet Users"]; } )]);
	
	//xAxis
	svg.append("g")
		.attr("class","x axis")
		.attr("transform", "translate(0," + height + ")") 
		.call(xAxis)			
		.selectAll("text")
			.style("text-anchor", "end")
			.attr("dx", "-.8em")
			.attr("dy", ".15em")
			.attr("transform", "rotate(-35)");
	//yAxis
	svg.append("g")
		.attr("class","y axis")
		.call(yAxis);
	
	//x axis label
	svg.append("text")
		.attr("x", width/2)
		.attr("y", height + margin.bottom)
		.text("Year");
	
	//y axis label
	svg.append("text")
        .attr("transform", "rotate(-90)")
		//NOTE - we actually rotate our reference point by 90 degrees
		//https://www.d3noob.org/2012/12/adding-axis-labels-to-d3js-graph.html gives more detail
	.attr("y", 0 - margin.left)
        .attr("x",0 - (height / 2))
        .attr("dy", "1em")
        .style("text-anchor", "middle")
        .text("Number of Users (billions)");

//title
	svg.append("g")
	.attr("class","title")
	.append("text")
	.attr("x", width/2)
	.attr("y", (margin.top / 2))
	.attr("text-anchor", "middle")
	.text("Internet users over time")

svg.selectAll(".bar")
	.data(data)
	.enter()
	.append("rect")
	.attr("class", "bar")
	.attr("x", function(d) {return xScale(d.Year);})
	.attr("y", function(d) {return yScale(d["Internet Users"]); })
	.attr("width",xScale.rangeBand())
	.attr("height", function (d) {return height - yScale(d["Internet Users"]);  })
	//show and hide tooltip
	.on("mouseover", tip.show)
	.on("mouseout", tip.hide) ;	
});
function type(d) {
		d.Penetration = d.Penetration;
		return d;
	}
</script>
</body>
</html>

Modified http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js to a secure url

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

https://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js