javascript - Regex to match begining of string with set endings or not -

looking regex match whatever @ beginning of string minus 1 of following set endings:

_a _b _c _zz 

so example:

1. blah         needs match blah 2. blah_a       needs match blah 3. blahblah_a   needs match blahblah 4. blah_d       needs match blah_d 5. blah_z       needs match blah_z 6. blah_zz      needs match blah 7. blah_ablah   needs match blah_ablah 

unsuccessful attemps have tried are:

.*(?=(_(a|b|c|zz)))   did not match 1,4,5, , 7 correctly  .*([^(_a$)]|[^(_b$)]|[^(_c$)]|[^(_zz$)])   did not match correctly 

regex vesrion used javascript

anyone got ideas?

the problem .* can consume entire string (and will). simplest fix make repetition ungreedy , require end of string after optional _ endings:

.*?(?=(_(a|b|c|zz))?$) 

this way .* won't consume ending characters if should excluded.

working demo.

as minor optimisation, avoid capturing group (if don't need it) , use character class, single-character endings:

.*?(?=(?:_(?:[abc]|zz))?$)