Regular Expressions 101

Positive Lookahead(?=\d{1,2}\s*(?:h|m))

\d{1,2}a digit, repeated between 1 and 2 times

\s*any whitespace character, repeated any number of times

Non-Capturing Group(?:h|m)

1st Alternativeh

hthe literal h (104₁₀ / 150₈ / 68₁₆) (case sensitive)

2nd Alternativem

mthe literal m (109₁₀ / 155₈ / 6D₁₆) (case sensitive)

Non-Capturing Group(?:(\d{1,2})\s*h)?

?repeats the group contents below at most once:

Group 1(\d{1,2})

\d{1,2}a digit, repeated between 1 and 2 times

\s*any whitespace character, repeated any number of times

hthe literal h (104₁₀ / 150₈ / 68₁₆) (case sensitive)

\s*any whitespace character, repeated any number of times

Non-Capturing Group(?:\s?(\d{1,2})\s*m)?

?repeats the group contents below at most once:

\s?optionally matches any whitespace character

Group 2(\d{1,2})

\d{1,2}a digit, repeated between 1 and 2 times

\s*any whitespace character, repeated any number of times

mthe literal m (109₁₀ / 155₈ / 6D₁₆) (case sensitive)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(?=\d{1,2}\s*(?:h|m))(?:(\d{1,2})\s*h)?\s*(?:\s?(\d{1,2})\s*m)?

8h20m 10m 8h left 
  8 h     30 m left
8h left
8h 20m left
57m left
1m left