fix calculateColor function

Fix sorting co2Scale to not be in place, change finding scaleIndex to be equal to closestNum (not greater than).

5-browser-extension/3-background-tasks-and-performance/README.md

@@ -65,11 +65,11 @@ function calculateColor(value) {
 	let co2Scale = [0, 150, 600, 750, 800];
 	let colors = ['#2AA364', '#F5EB4D', '#9E4229', '#381D02', '#381D02'];
 
-	let closestNum = co2Scale.sort((a, b) => {
+	let closestNum = co2Scale.slice().sort((a, b) => {
 		return Math.abs(a - value) - Math.abs(b - value);
 	})[0];
 	console.log(value + ' is closest to ' + closestNum);
-	let num = (element) => element > closestNum;
+	let num = (element) => element === closestNum;
 	let scaleIndex = co2Scale.findIndex(num);
 
 	let closestColor = colors[scaleIndex];