1.利用 for 循环
var sum = 0; for (var i = 1; i <= 100; i++) { sum += i; } console.log(sum); // > 5050
2.利用 while 循环
var sum = 0; var i = 1; while (i <= 100) { sum += i; i++; } console.log(sum); // > 5050
3.递归累加函数
function accumulation(start, end) { if (start === end) { return end; } return start + accumulation(start + 1, end); } console.log(accumulation(1, 100)); // > 5050