moving to arrow functions

app.js

@@ -19,7 +19,7 @@ var dAttributeFunction = d3.geoPath()
 d3.selectAll('path').attr('d', dAttributeFunction);
 
 var dragBehavior = d3.drag() //create a drag behavior
-	.on('start', function(event){
+	.on('start', (event) => {
 		d3.select('table tr:nth-child(2) td:first-child')
 			.html(worldProjection.invert([event.x, event.y])[0])
 		d3.select('table tr:nth-child(2) td:last-child')
@@ -30,7 +30,7 @@ var dragBehavior = d3.drag() //create a drag behavior
 			.attr('x', event.x)
 			.attr('y', event.y);
 	})
-	.on('drag', function(event){
+	.on('drag', (event) => {
 		d3.select('table tr:nth-child(3) td:first-child')
 			.html(worldProjection.invert([event.x, event.y])[0])
 		d3.select('table tr:nth-child(3) td:last-child')
@@ -42,7 +42,7 @@ var dragBehavior = d3.drag() //create a drag behavior
 
 d3.select('svg').call(dragBehavior);
 
-d3.select('form').on('submit', function(event){
+d3.select('form').on('submit', (event) => {
 	event.preventDefault();
 
 	d3.selectAll('rect').remove();