找出二维数组中每一项的最大值#

function fnArr(arr){
  const newArr = [];
  arr.forEach((item,index)=>{
    newArr.push( Math.max(...item)  )
  })
  return newArr;
}
console.log(fnArr([
  [4,5,1,3],
  [13,27,18,26],
  [32,35,37,39],
  [1000,1001,857,1]
]));