left axis

public/css/app.css

@@ -1,5 +1,8 @@
+body {
+	padding: 0 2em;
+}
 svg {
-	border:1px solid black;
+	overflow: visible;
 }
 circle {
 	r: 5;

public/js/app.js

@@ -92,3 +92,8 @@ d3.select('svg').on('click', function(){
 			render
 		);
 });
+
+var leftAxis = d3.axisLeft(convertYDataPointToVisualPoint); //create a left axis based on the yScale
+d3.select('svg')
+	.append('g') //append a group element
+	.call(leftAxis); //apply the axis to it