Javascript split with RegEx

Question

I just asked a question about Regex, and received a great answer: JavaScript Split without losing character

Now, I have another question.

My current Regex looks like this:

var split = text.split(/(?=\w*\d*\d:\d\d)/);

Basically, I'm trying to split using the timestamps (eg - 9:30 or 10:30, the difference between them is the extra digit in the latter). How do I go about this?

Currently, if I have these two:

9:30 pm
The user did action A.

10:30 pm
Welcome, user John Doe.

The splits are :

9:30 pm
The user did action A.
----
1
----
0:30 pm
Welcome, user John Doe.

How do I add an optional check for the first character in the timestamp?

Thanks!

Browsers have all sorts of incompatibilities in the ways that split() works when the argument is a regex. See this: blog.stevenlevithan.com/archives/cross-browser-split — Pointy
– Pointy, Commented Jun 15, 2010 at 18:25

Community · Accepted Answer · 2017-05-23 12:30:47Z

1

See my answer to your other question, I fixed this problem in the regex by adding a word boundary:

var split = journals.split(/\s*(?=\b\d+:)/);

Updated it with \s* to strip out any unnecessary whitespace (but not the line breaks) too. Result:

["9:30 pm    
The user did action A.", "10:30 pm  
Welcome, user John Doe.", "11:30 am
Messaged user John Doe"]

edited May 23, 2017 at 12:30

CommunityBot

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answered Jun 15, 2010 at 18:49

Andy E

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Vivin Paliath · Accepted Answer · 2010-06-15 17:56:27Z

1

var split = text.split(/(?=\w*[\d]{1,2}:[\d]{2})/);

RegexPal is helpful for these tasks.

edited Jun 15, 2010 at 17:56

Vivin Paliath

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answered Jun 15, 2010 at 17:55

Andy

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1 Comment

Andy Over a year ago

Which doesn't -- that pattern or the site? If you are using the site, you need to just put in the pattern, i.e. (\w*\d*\d:\d\d) will match the input you gave.

Andy E · Accepted Answer · 2010-08-17 16:44:28Z

1

I'm not clear on what you're trying to do to the text, but I do have a regex that hopefully can help match the times only.

\d{1,2}:\d{1,2} (am|pm)

The problem with your regex and andy's regex is that the * is greedy. It means zero or more matches, as many times as possible. Using {min,max} with the exact numbers you need will be more accurate and avoid the greedy *.

edit: Andy's does in fact work on that site he linked. And the * doesn't seem to be greedy. Does either pattern work for you?

edited Aug 17, 2010 at 16:44

Andy E

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answered Jun 15, 2010 at 18:12

robertpateii

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1 Comment

Andy E Over a year ago

{min, max} was the first thing I tried. The real problem is the lookahead, it will look ahead and find 0:30 and split on that, instead of 10:30. Adding a required word boundary forces the lookahead to find where the "word" begins. +1 and welcome to Stack Overflow :-)

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