en.javascript.info/5-regular-expressions/12-regexp-anchors/2-test-mac/task.md

Check MAC-address

MAC-address of a network interface consists of 6 two-digit hex numbers separated by a colon.

For instance: subject:'01:32:54:67:89:AB'.

Write a regexp that checks whether a string is MAC-address.

Usage:

let reg = /your regexp/;

alert( reg.test('01:32:54:67:89:AB') ); // true

alert( reg.test('0132546789AB') ); // false (no colons)

alert( reg.test('01:32:54:67:89') ); // false (5 numbers, must be 6)

alert( reg.test('01:32:54:67:89:ZZ') ) // false (ZZ ad the end)