Update "Capturing groups" files

Author: odsantos

9-regular-expressions/11-regexp-groups/04-parse-expression/solution.md

@@ -10,8 +10,8 @@ The full regular expression: `pattern:-?\d+(\.\d+)?\s*[-+*/]\s*-?\d+(\.\d+)?`.
 
 It has 3 parts, with `pattern:\s*` between them:
 1. `pattern:-?\d+(\.\d+)?` - the first number,
-1. `pattern:[-+*/]` - the operator,
-1. `pattern:-?\d+(\.\d+)?` - the second number.
+2. `pattern:[-+*/]` - the operator,
+3. `pattern:-?\d+(\.\d+)?` - the second number.
 
 To make each of these parts a separate element of the result array, let's enclose them in parentheses: `pattern:(-?\d+(\.\d+)?)\s*([-+*/])\s*(-?\d+(\.\d+)?)`.
 
@@ -54,3 +54,17 @@ function parse(expr) {
 
 alert( parse("-1.23 * 3.45") );  // -1.23, *, 3.45
 ```
+
+As an alternative to using the non-capturing `?:`, we could name the groups, like this:
+
+```js run
+function parse(expr) {
+	let regexp = /(?<a>-?\d+(?:\.\d+)?)\s*(?<operator>[-+*\/])\s*(?<b>-?\d+(?:\.\d+)?)/;
+
+	let result = expr.match(regexp);
+
+	return [result.groups.a, result.groups.operator, result.groups.b];
+}
+
+alert( parse("-1.23 * 3.45") );  // -1.23, *, 3.45;
+```