creating render function

app.js

@@ -23,6 +23,8 @@ d3.select('svg')
     .style('width', WIDTH)
     .style('height', HEIGHT);
 
+var render = function(){
+
     var yScale = d3.scaleLinear();
     yScale.range([HEIGHT, 0]);
     yDomain = d3.extent(runs, function(datum, index){
@@ -53,6 +55,9 @@ d3.selectAll('circle')
             return xScale(parseTime(datum.date));
         });
         
+}
+render();
+
 var bottomAxis = d3.axisBottom(xScale);
 d3.select('svg')
 	.append('g')