nice style, will considered that within my next more complex RegExp.

no problem mate

nice change dude
this space reduction helped a lot

Java Translation now available :)

Java Translation translated to Java

check the given input variables in getSerie
One is an optional agrument

• No test with empty string.
• No tests without letters.
• No tests with wrong closing braces order (like "[ { ] }")

• no random tests
• not enough tests either (especially about the validation of the "strings"
• missing edge cases: H2)O for example

the verification of chemical elements provides zero significant challenge

would depend on how it's done. Tho that's not new and that's clearly not done the right way, here, yes.

The verification of braces balance is not new, and the verification of chemical elements provides zero significant challenge. Duplicate.

Concatentating a string throughout a loop is a bad practice and will result in poor performance.