refactor(charts.js): use key value map for handling chart types

src/scripts/charts.js

@@ -14,15 +14,24 @@ import Heatmap from './charts/Heatmap';
 // 	);
 // }
 
+const chartTypes = {
+	line: LineChart,
+	bar: BarChart,
+	scatter: ScatterChart,
+	percentage: PercentageChart,
+	heatmap: Heatmap
+};
+
+function getChartByType(chartType = 'line', options) {
+	if (!chartTypes[chartType]) {
+		return new LineChart(options);
+	}
+
+	return new chartTypes[chartType](options);
+}
+
 export default class Chart {
 	constructor(args) {
-		switch (args.type) {
-			case 'line': return new LineChart(arguments[0]);
-			case 'bar': return new BarChart(arguments[0]);
-			case 'scatter': return new ScatterChart(arguments[0]);
-			case 'percentage': return new PercentageChart(arguments[0]);
-			case 'heatmap': return new Heatmap(arguments[0]);
-			default: return new LineChart(arguments[0]);
-		}
+		return getChartByType(args.type, arguments[0]);
 	}
 }