Rocket Chat Search Basics

Introduction

Rocket Chat search supports the use of "regular expressions", the benefits of which are great search flexibility and the ability to search chat entries in any language, even ones which are traditionally a challenge for search (e.g. "CJK" languages - Chinese, Japanese, Korean).

Basic Regex Examples

Regular expressions are a deep, but admittedly geeky topic. The flexibility of "regex" search increases as you learn more about how to write regex patterns, but if you learn just a couple of simple patterns, you can benefit right away.

Let's see a few simple examples that you can try.

"Bare" word search

You can simply enter a search term in the search box and press enter. This works in many cases, but not for CJK-type languages.

Find the capitalized string "BTW"

Enter /BTW/ to find the capitalized variant of a search string. The slashes // bookend the string, and tell the system "this is a regex pattern".

Find a CJK string

Enter a CJK language string between slashes, like /ブラジル連邦共和国/ (Japanese for República Federativa do Brasil), and Rocket Chat search will return posts with that string.

N.b. - CJK users should be careful to use standard ASCII slashes, and not any unicode variants. That is, / but not a double-byte ／, as the latter will not work.

Find "BTW" or "btw"

Enter /BTW/i with a trailing "i", meaning "ignore case". Actually, it works for "Btw" or "bTw" etc, too.

Find "BTW" in specific positions

Enter /^BTW/i to find posts with "BTW" or "btw" anchored to the beginning of the post. The ^ is the start anchor.

Enter /BTW$/i to find posts with "BTW" or "btw" anchored to the end of the post. The $ is the end anchor.

Find word variants

Enter /^Any(body|one)/i to find posts that start with "Anybody" or "Anyone". The (body|one) bit means to find "body" or "one".

Enter /(nginx|apache)/i to find posts with either "nginx" or "apache".

Enter /(東京|京都)/i to find posts with either "Tokyo" or "Kyoto".

Find a string surrounded by spaces

Enter /\s+123456\s+/i to find " 123456 " with a space before and after.

Conclusion

Those are enough examples to get you started. If you're interested, please use the following references to learn more about the deep world of regex.

Reference

Wikipedia - https://en.wikipedia.org/wiki/Regular_expression
Regex 101 - https://regex101.com/#javascript
Regexr - http://regexr.com/
Regex Info - http://www.regular-expressions.info/javascriptexample.html

RickCogley/Rocket Chat Regex Search Basics.md