How to build regex for not returning empty string if none of the groups return result

user_4614264 0
Viewed 93

I'm trying to build a regex to match timesheet hours entry where user enters his hours in the format 20h 50m.

In this format, the user can either enter hours only 20h, or minutes only 50m or both hours and minutes 20h 50m.

Sample matches

45m
1h
2h 45m

The numbers can be anything other than 20 or 50.

I came up with this regex ((([0-9]+h)\s([0-9]+m))|([0-9]+h)|([0-9]+m)){1}, which is long and I'm trying to reduce it.

So I tried different solution: ((\d+h)?([\s]*(\d+m))?) https://regex101.com/r/ZEBsle/1/ .But the issue with this solution is that it matches empty strings and doesn't match patterns like 2h 45m.

How can I modify the last regex so it can match the following formats?

45m
1h
2h 45m
javascript regex
3 Answers

Here's my take at it:

/(?<=\b)\d+h \d+m|\d+[hm](?=\b)/g

Example on Regex101

const str = `45m
1h
4h 35m
some text before 2h 45m and after
travelled 66miles
2m 45h this one are inversed, so treat them separately
245m`;

const times = str.match(/(?<=\b)\d+h \d+m|\d+[hm](?=\b)/g);
console.log(times);

user_3839040 
\d+h\s\d+m|\d+h|\d+m

I think it will work.

user_126663570

To match all variations, you could use

\b(?:\d+h(?: \d+m)?|\d+m)\b

Explanation

  • \b A word boundary
  • (?: Non capture group
    • \d+h Match 1+ digits and h
    • (?: \d+m)? Optionally match a minute part
    • | Or
    • \d+m Match 1+ digits and m
  • ) Close group
  • \b A word boundary

Regex demo

If you want to match hours and minutes in that order, you might use anchors ^ and $

^(?:\d+h(?: \d+m)?|\d+m)$

Regex demo

user_54249880
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