find in highest value key from an object javascript

1Math.max.apply(Math, array.map(function(o) { return o.y; }))

1var obj = {a: 1, b: 2, undefined: 1};
2
3Object.keys(obj).reduce((a, b) => obj[a] > obj[b] ? a : b);

1var obj = {a: 1, b: 2, undefined: 1};
2
3Object.keys(obj).reduce((a, b) => obj[a] > obj[b] ? a : b);
4