I’ve seen tools like this one before, but every time I do I still pass them around because regular expressions are powerful but also quite unapproachable. With this library, you can chain together function calls describing how you think about a rule and it’ll generate the expression for you. Example!

const SuperExpressive = require('super-expressive');

const myRegex = SuperExpressive()
  .startOfInput
  .optional.string('0x')
  .capture
    .exactly(4).anyOf
      .range('A', 'F')
      .range('a', 'f')
      .range('0', '9')
    .end()
  .end()
  .endOfInput
  .toRegex();

// Produces the following regular expression:
/^(?:0x)?([A-Fa-f0-9]{4})$/

That matches and captures the value of a 16-bit hexadecmal number like 0xC0D3. Assuming this library generates clean, somewhat optimal expressions (which might be a big assumption), it’s a great way to learn how to write your own expressions over time.