how to capture from group from end line in js regex? - regex

Question

I'm trying to capture a text into 3 groups I have managed to capture 2 groups but having an issue with the 3rd group.
This is the text :
<13>Apr 5 16:09:47 node2 Services: 2016-04-05 16:09:46,914 INFO [3]
Drivers.KafkaInvoker - KafkaInvoker.SendMessages - After sending
itemsCount=1
I'm using the following regex:
(?=- )(.*?)(?= - )|(?=])(.*?)(?= -)
My 3rd group should be : "After sending itemsCount=1"
any suggestions?

Answer 1

Your original expression is fine, just missing a $:
(?=- )(.*?)(?= - |$)|(?=])(.*?)(?= -)
Demo
and maybe we would slightly modify that to an expression similar to:
(?=-\s+).*?([A-Z].*?)(?=\s+-\s+|$)|(?=]\s+).*?([A-Z].*?)(?=\s+-)
Demo

Answer 2

You have 2 capturing groups. You don't get the match for the third part because the postitive lookahead in the first alternation is not considering the end of the string. You might solve that by using an alternation to look at either a space or assert the end of the string
(?=[-\]] )(.*?)(?= - |$)
^^
If those matches are ok, you could simplify that pattern by making use of a character class to match either - or ] like [-\]] and omit the alternation and the group as you now have only the matches.
Your pattern then might look like (also capturing the leading hyphen like the first 2 matches)
(?=[-\]] ).*?(?= - |$)
Regex demo
If this is your string and you want to have 3 capturing groups, you might use:
^.*?\[\d+\]([^-]+)-([^-]+)-\s*([^-]+)$
^ Start of string
.*? Match any char except a newline non greedy
\[\d+\] match [ 1+ digits ]
([^-]+)- Capture group 1, match 1+ times not -, then match -
([^-]+)- Capture group 2, match 1+ times not -, then match -
\s* Match 0+ whitespace chars
([^-]+) Capture group 2, match 1+ times not -
$ End of string
Regex demo
For example creating the desired object from the comments, you could first get all the matches from match[0] and store those in an array.
After you have have all the values, assemble the object using the keys and the values.
var output = {};
var regex = new RegExp(/(?=[-\]] ).*?(?= - |$)/g);
var str = `<13>Apr 5 16:09:47 node2 Services: 2016-04-05 16:09:46,914 INFO [3] Drivers.KafkaInvoker - KafkaInvoker.SendMessages - After sending itemsCount=1`;
var match;
var values = [];
var keys = ['Thread', 'Class', 'Message'];
while ((match = regex.exec(str)) !== null) {
// This is necessary to avoid infinite loops with zero-width matches
if (match.index === regex.lastIndex) {
regex.lastIndex++;
}
values.push(match[0]);
}
keys.forEach((key, index) => output[key] = values[index]);
console.log(output);