使用map返回每个数组中的最大值

function each(coll, f) {
  if (Array.isArray(coll)) {
    for (var i = 0; i < coll.length; i++) {
      f(coll[i], i);
    }
  } else {
    for (var key in coll) {
      f(coll[key], key);
    }
  }
}

function map(array, f) {
  var acc = [];
  each(array, function(element, i) {
    acc.push(f(element, i));
  });
  return acc;
}

function max(numbers) {
  var maximum = numbers[0];
  each(numbers,function(x){
    if(x>maximum){
      maximum = x;}
  });
  return maximum;
}

function maximums(arrays){
  return map(arrays, function(x){
    return max(arrays);
  })
}

maximums([1,2,3],[5,6,7])
function each(coll, f) {
  if (Array.isArray(co