Question

I’m struggling to create a regex expresion in Javascript to match values between 5pt and 30pt.

That is 5pt, 6pt, 7pt, …, 29pt and 30pt. The value should have a number between 5 and 30 followed by pt.

Answer 1

This will match anything from 5-30 and will not match things like 35pt. So far in the above regexes provided, only Andrew’s method avoids false positives like matching “35pt” as “5pt”.

var re = /(?:^|[^0-9])((?:30|[12][0-9]|[5-9])pt)/i
var text = "5pt 25pt 30pt 35pt";
while (result = re.exec(text)) {
  console.log(result[1]);
}
// returns 5pt, 14pt, 30pt

where your match is in the first backreference. Note the importance of screening for things like other numbers before.

If you’re indifferent to false positives like that, try

/(?:30|[12][0-9]|[5-9])pt)/

where the entire match is what you’re looking for.