using variable to retrieve item from array

Question

I am wanting to set a variable to change the number value to get the correct array item

Console.log this and i get what i need, but any attempts made to add a variable are not working

// This works
lastKickoffTime = m_nfl_schedule_ar.w_5.slice(-1).pop().kickoff

Attempts that have not worked

weekNum = "5";

lastKickoffTime = m_nfl_schedule_ar.['w_'+weekNum].slice(-1).pop().kickoff

lastKickoffTime = m_nfl_schedule_ar.w_[weekNum].slice(-1).pop().kickoff

lastKickoffTime = m_nfl_schedule_ar.w_weekNum.slice(-1).pop().kickoff

lastKickoffTime = m_nfl_schedule_ar.w_+weekNum+.slice(-1).pop().kickoff

lastKickoffTime = m_nfl_schedule_ar.w_'+weekNum+'.slice(-1).pop().kickoff

Answer 1

lastKickoffTime = m_nfl_schedule_ar.['w_'+weekNum].slice(-1).pop().kickoff is almost right. should be:

lastKickoffTime = m_nfl_schedule_ar['w_'+weekNum].slice(-1).pop().kickoff