join

// Name(Account) joined our world. Diablo's minions grow stronger.

RegisterEvent(EVENT_GAMEMSG,
    function (msg, type) {
        if (type === 4 && msg.indexOf('stronger') > -1) { // join message
            var userName = msg.split('(')[0];   // split is ["Name", "Account) joined our world. Diablo's minions grow stronger."]
                                                // split[0] is "Name"

            // for reference only, can be done in one line with 2 splits as well - var userAccount = msg.split('(')[1].split(')')[0];
            var userAccount = msg.split('(')[1];    // split is ["Name", "Account) joined our world. Diablo's minions grow stronger."]
                                                    // split[1] is "Account) joined our world. Diablo's minions grow stronger."
                userAccount = userAccount.split(')')[0];    // split is ["Account", " joined our world. Diablo's minions grow stronger."]
                                                            // split[0] is "Account"

            Print(userName + " " + userAccount);
            Say("/ignore " + userName);
        }
    }
);