iterate array - sum / contact with reduce

iterate array - sum / contact with reduce

http://learnjsdata.com/iterate_data.html

var landSum = data.reduce((sum, d)=> sum + d.land_area, 0);
console.log(landSum);

var weirdString = data.reduce(function(str, d, i) {
  var ending = (i % 2 === 0) ? " is cool." : " sucks." ;
  return str.concat( " " , d.city , ending)
}, "");
console.log(weirdString);