I don’t want to repeat repeat myself

Yesterday at work, a customer spotted a typo in our UI: “you can use the use the Tailscale CLI”. After the typo was fixed, I wanted to find other cases of accidentally repeated words or phrases. I used two regular expressions to search every codebase for unnecessary repetition.

The first regex finds repeated words:

\b([A-Za-z]+) \1\b

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There’s a capturing group for a single word made up of letters ([A-Za-z]+), a space, then a backreference to the group.

That expression is surrounded by word boundary assertions \b, which check that I’m at the start/end of a word – this avoids finding repeated character sequyences that within longer words, like “with the reason”.

The second regex finds repeated phrases:

\b([A-Za-z]+ [A-Za-z]+) \1\b

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I’ve changed the capturing group, so now it looks for two words separated by a space.

Sometimes repetition is useful, like when I really really went to emphasise a point, but often it’s just a typo. Cleaning up these mistakes has been a fun Friday cleanup task.