Sumproduct数组

Question

我正在做这段代码：

Class Cash
{
    constructor(v, q)
    {
     this.value = v;
     this.quantity = q;
    }

    var money = [];
    money.push( new Cash(50, 4);
    money.push( new Cash(20, 4);
    money.push( new Cash(10, 2);

我需要这样做：

(money[0].value * money[0].quantity) + (money[1].value * money[1].quantity) + (money[n].value * money[n].quantity)

3个数组的预期结果是300 (50 * 4) + (20 * 4) + (10 * 2)

这个想法是，无论我把多少东西放入货币中，它都会继续做push乘积

我试过了，但不起作用：

for (i = 0; i > money.length; i++)
{
    (money[i].value * money[i].quantity) + (money[i++].value * money[i++].quantity)
}

Answer 1

简单的for循环

var total = 0;
for( var i =0; i< money.length; i++) {
  total += money[i].value * money[i].quantity;
}
console.log(total);

或者使用reduce

const total = money.reduce(function (total, item) {
  return total + item.value * item.quantity;
}, 0);
console.log(total);

Answer 2

您可以按如下方式使用函数Array.prototype.reduce：

​

class Cash {
  constructor(v, q) {
    this.value = v;
    this.quantity = q;
  }
}

const money = [new Cash(50, 4), new Cash(20, 4), new Cash(10, 2)],
      result = money.reduce((a, m) => a + (m.value * m.quantity), 0);

console.log(result);

​

Answer 3

请参阅下面的注释以获取修复。

​

class Cash { /* class, not Class */
  constructor(v, q) {
    this.value = v;
    this.quantity = q;
  }
} /* close your class declaration */

const money = [];
money.push(new Cash(50, 4)); /* close your parenthesis */
money.push(new Cash(20, 4)); /* close your parenthesis */
money.push(new Cash(10, 2)); /* close your parenthesis */

let sum = 0; /* initialize a sum variable with value 0 to retain results */
for (m of money) { /* or for (let i = 0; i < money.length; i++)
  /* Assign result of sum/product to something
   * More accurately add it to sum */
  sum += m.value * m.quantity;
}
console.log(sum);

​