练习1:求数组中所有元素的和
var arr1 = [10, 20, 30, 40, 50];
var sum = 0;
for (var i = 0; i < arr1.length; i++) {
sum += arr1[i];
}
console.log(sum);
练习2:求数组中所有元素的平均值
var arr2 = [1, 2, 3, 4, 5];
var sum2 = 0;
for (var i = 0; i < arr2.length; i++) {
sum2 += arr2[i];
}
console.log(sum2 / arr2.length);