找出多维数组最大值

function fnArr(arr){
	var 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]
]));