var -> const

app.js

@@ -1,11 +1,11 @@
-var width = 960;
-var height = 490;
+const width = 960;
+const height = 490;
 
 d3.select('svg')
     .attr('width', width)
     .attr('height', height);
 
-var worldProjection = d3.geoEquirectangular();
+const worldProjection = d3.geoEquirectangular();
 
 d3.select('svg').selectAll('path')
     .data(map_json.features)
@@ -13,12 +13,12 @@ d3.select('svg').selectAll('path')
     .append('path')
     .attr('fill', '#099');
 
-var dAttributeFunction = d3.geoPath()
+const dAttributeFunction = d3.geoPath()
     .projection(worldProjection);
 
 d3.selectAll('path').attr('d', dAttributeFunction);
 
-var dragBehavior = d3.drag() //create a drag behavior
+const dragBehavior = d3.drag() //create a drag behavior
 	.on('start', (event) => {
 		d3.select('table tr:nth-child(2) td:first-child')
 			.html(worldProjection.invert([event.x, event.y])[0])