关于javascript:JavaScript数组求和的常用方法

JS 数组求和的罕用办法。

一、for 循环

var arr = [1,2,3];
function sum(arr) {
  var s = 0;
  for (var i = 0;i<arr.length;i++) {s += arr[i];
  }
  return s;
}
console.log(sum(arr));//6

二、forEach 遍历

var arr = [1,2,3];
function sum(arr) {
  var s = 0;
  arr.forEach(function(val, idx, arr) {s += val;}, 0);
  return s;
};
console.log(sum(arr));//6

三、reduce

var arr = [1,2,3];
function sum(arr) {return arr.reduce(function(acr, cur){return acr + cur;});
}
console.log(sum(arr));//6

四、递归

var arr = [1,2,3];
function sum(arr) {if(arr.length == 0){return 0;} else if (arr.length == 1){return arr[0];
  } else {return arr[0] + sum(arr.slice(1));
  }
}
console.log(sum(arr));//6

五、eval

var arr = [1,2,3];
function sum(arr) {return eval(arr.join("+"));
};
console.log(sum(arr));//6