方法一:通过原型对象扩展内置对象方法(即给Array增加方法)
- Array.prototype.sum = function () {
- var sum = 0;
- for (var i = 0; i < this.length; i++) {
- sum += this[i];
- }
- return sum;
- };
- var arr = [1, 2, 3, 4];
- console.log(arr.sum()); // 10
方法二:普通for循环函数求和
- function sum(arr) {
- var sum = 0;
- for (var i = 0; i < arr.length; i++) {
- sum += arr[i];
- }
- return sum;
- }
- var arr = [1, 2, 3, 4];
- console.log(sum(arr)); // 10
方法三:使用递归
- function sum(arr) {
- if (arr.length == 0) {
- return 0; // 递归出口
- } else {
- return arr[0] + sum(arr.slice(1));
- }
- }
- var arr = [1, 2, 3, 4];
- console.log(sum(arr)); // 10
方法四:函数式编程reduce
- function sum(arr) {
- return arr.reduce(function (total, value) {
- return total + value;
- }, 0);
- }
- var arr = [1, 2, 3, 4];
- console.log(sum(arr)); // 10
-
方法五:forEach遍历
- function sum(arr) {
- var s = 0;
- arr.forEach(function (value) {
- s += value;
- });
- return s;
- }
- var arr = [1, 2, 3, 4];
- console.log(sum(arr)); // 10
方法六:eval()方法
- function sum(arr) {
- return eval(arr.join("+"));
- }
- var arr = [1, 2, 3, 4];
- console.log(sum(arr)); // 10