js获取最大值

var data = [1, 5, 3, 6, 3, 6, 8, 15, 3, 5];
    var maxNum = null;
    var num = 0;
    for (var i = data.length; i--;) {
      if (data[i] > num) {
        num = data[i];
        maxNum = data[i];
      }
    }
    console.log(maxNum)  //15