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Editorial Team
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Asked: 2026-05-16T00:23:17+00:00

I’m trying to extract CSS positions from a string – example: top left bottom

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I’m trying to extract CSS positions from a string – example:

"top left bottom right center 0 0% 50% 100% 360deg 15.5% -16.3%"

The problem is that the string also contains an angle “360deg”. I don’t want any numbers followed by “deg” to be matched by the regular expression. Currently, I have:

(-?([0-9]*\.[0-9]+|[0-9]+))|(center)|(top)|(left)|(bottom)|(right)

This matches all the numbers (inc. the angle – which I don’t want). I have tried using a negative lookahead:

(-?([0-9]*\.[0-9]+|[0-9]+))(?!deg)|(center)|(top)|(left)|(bottom)|(right)

But this only appears to remove the ending zero from 360deg – i.e. 360deg => 36

Does anyone know why the negative lookahead is not successful in removing the angle?

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1 Answer

  1. Editorial Team

    The regular expression matches because it found two digits not followed by “deg”: The 36 is followed by 0 and that isn’t “deg”. The [0-9]* is usually greedy but if this causes the match to fail it will try alternatives matching fewer digits.

    You can change the negative lookahead to this:

    (?!deg|[0-9.])
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