how to calcuate seconds left in the current minute of the time

I want to update a clock in the UI when the time changes from `12:01` to `12:02`. I can do a setInterval every 60 seconds, but the beginning might not be on the first second of a new minute. How can I ensure that it starts at the first second? I think I need to find out how many seconds are left in the current minute and then do a setTimeout that fires setInterval when the seconds elapse. ``` var secondsLeft = ?; //calculate seconds left in this minute setTimeout(function(){ setInterval(function(){ //update clock }, 1000 * 60); }, secondsLeft); ``` If `moment.js` makes it easier, that's fine with me.