Merge pull request #268 from piman51277/patch-1

Optimize isNumber util func

src/util/isNumber.ts

@@ -1,4 +1,9 @@
 export default function (str: string | number): str is number {
-	// Although it doesn't check for decimals, it is not required here.
-	return typeof str === 'number' || /^\d+$/.test(str);
+	/** Why this works:
+	 *  1. Any non-NaN number is not NaN
+	 *  2. isNaN considers any numeric string to be not NaN
+	 * See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isNaN
+	 * for further reference
+	 */
+	return !isNaN(str as number);
 }