The (?!<=) means that the stuff preceeding it mustn't be followed by '<='. Your example is, so it doesn't match. Remove either or both chars or change one or both to something else and it will match.

/
    ^              # start of line
    \s*            # optional whitespace
    (?!for all)    # NOT "for all"
    (\w+)          # One or more word chars
    \s*            # optional whitespace
    :              # a colon
    \s*            # more optional whitespace
    (\w+)          # another set of one or more word chars
    \s*            # and more optional whitespace
    (?!<=)         # NOT followed by the char sequence '<='
/i
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right
I just re-read my original question and of course what I meant was why does it match?

When I run the above pattern it does match

The reason it matches is because the immediate preceeding whitespace is optional \s*. Therefore the parser can choose to say that if there is no whitespace, then the next char after the second (\w+) is a space, which isn't '<=' so therefore is can match, so it does.

Change that to be if (/^\s*(?!for all)(\w+)\s*:\s*(\w+)\s+(?!<=)/i) { and it no longer can match, so it doesn't (if you get my drift.

I realise that may or may not help you.

++Jasper below. I couldn't find a way of doing that. The caveat is that if you wanted to match

'cidr_enable: en_core_id == NOT(dsp_reset_n) AND <= stuff;'

your out of luck.

---

Nah! You're thinking of Simon Templar, originally played (on UKTV) by Roger Moore and later by Ian Ogilvy

/^\s*(?!for all)(\w+)\s*:\s*(\w+)\s*(?!.*<=)/i
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