components

9-regular-expressions/09-regexp-groups/3-find-decimal-positive-numbers/solution.md

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+
+An non-negative integer number is `pattern:\d+`. We should exclude `0` as the first digit, as we don't need zero, but we can allow it in further digits.
+
+So that gives us `pattern:[1-9]\d*`.
+
+A decimal part is: `pattern:\.\d+`.
+
+Because the decimal part is optional, let's put it in parentheses with the quantifier `pattern:'?'`.
+
+Finally we have the regexp: `pattern:[1-9]\d*(\.\d+)?`:
+
+```js run
+let reg = /[1-9]\d*(\.\d+)?/g;
+
+let str = "1.5 0 -5 12. 123.4.";
+
+alert( str.match(reg) );   // 1.5, 0, 12, 123.4
+```