<prompt> Unda chaguo la kukokotoa la JavaScript ambalo huchukua mfuatano kama ingizo na hukagua ikiwa ni anwani halali ya IPv4. Rejesha kweli ikiwa ni halali, sivyo vinginevyo.  <response>: kazi isValidIPv4str const regex 250-520-40-901?0-90-9?.325? 0-520-40-901?0-90-9?; rudisha regex.teststr; Mfano wa matumizi:console.logisValidIPv4192.168.1.1; kweliconsole.logisValidIPv4255.255.255.255; kweliconsole.logisValidIPv4256.0.0.0; uongo 