don't wipe points and table each render

public/app.js

@@ -8,10 +8,9 @@ const parseTime = d3.timeParse("%B %e, %Y");
 const formatTime = d3.timeFormat("%B %e, %Y");
 
 const renderTable = () => {
-	d3.select('tbody').html('');
 	const trs = d3.select('tbody')
 		.selectAll('tr')
-		.data(instances.filter(d => d.highlighted))
+		.data(instances.filter(d => d.highlighted), d => d.id)
 		.enter()
 		.append('tr')
 		.selectAll('td')
@@ -22,10 +21,9 @@ const renderTable = () => {
 }
 
 const renderPoints = () => {
-	d3.select('#points').html('');
 	const circles = d3.select('#points')
 		.selectAll('circle')
-		.data(instances)
+		.data(instances, d => d.id)
 		.enter()
 		.append('circle');