js取数组最大值

var arr = [-1, 1, 101, -52, 10, 1001, 1001];
Math.max(...arr);   // 1001

var arr = [-1, 1, 101, -52, 10, 1001, 1001],
    max;
arr.forEach((item, i) => {
    max = item > arr[i] ? item : arr[i];
}); 
console.log(max);   // 1001

var arr = [-1, 1, 101, -52, 10, 1001, 1001];
arr.sort((a, b) => {
    return b - a;
});
console.log(arr[0]);   // 1001

var arr = [-1, 1, 101, -52, 10, 1001, 1001],
max = arr.reduce((pre, item) => {
    return pre > item ? pre : item}
);
console.log(max);   // 1001