How to match a string not followed by a preceeding word?

How to match a string not followed by a preceeding word?

This should pass the condition:
kword_search = doesnt matter if
kword_search = doesnt matt er if
kword_search = doesnt m atter if
This should not:
kword_search = doesnt matter else if
kword_search = doesnt matter else if
kword_search = doesnt matter else else if
What i've done so far:
/\*(^else)\s+if$/.test(kword_search)