style: add castToNumber method

Author: wrn14897

packages/app/src/hooks/useChartConfig.tsx

@@ -52,30 +52,22 @@ export const splitChartConfigs = (config: ChartConfigWithOptDateRange) => {
   return [config];
 };
 
-export const computeRatio = (
-  numeratorInput: string | number,
-  denominatorInput: string | number,
-) => {
-  let numerator: number;
-  let denominator: number;
-
-  if (typeof numeratorInput === 'string') {
-    if (numeratorInput.trim() === '') {
+const castToNumber = (value: string | number) => {
+  if (typeof value === 'string') {
+    if (value.trim() === '') {
       return NaN;
     }
-    numerator = Number(numeratorInput);
-  } else {
-    numerator = numeratorInput;
+    return Number(value);
   }
+  return value;
+};
 
-  if (typeof denominatorInput === 'string') {
-    if (denominatorInput.trim() === '') {
-      return NaN;
-    }
-    denominator = Number(denominatorInput);
-  } else {
-    denominator = denominatorInput;
-  }
+export const computeRatio = (
+  numeratorInput: string | number,
+  denominatorInput: string | number,
+) => {
+  const numerator = castToNumber(numeratorInput);
+  const denominator = castToNumber(denominatorInput);
 
   if (isNaN(numerator) || isNaN(denominator) || denominator === 0) {
     return NaN;