返回NAN的JavaScript类中的乘法方法

Question

我在一个JavaScript类中有一个乘法方法，它应该将数组中非未定义的所有元素相乘。我使用for loop检查每个元素的类型，即number并将它们推到一个空数组，然后使用reduce方法将它们相乘。但我现在有的问题是结果是返回南。我想知道我做错了什么。

下面是我的代码。

null

class Calculator {

    add(numbers) {
        let result = [];
        for (const i in numbers) {
           if (typeof numbers[i] === "number"){
            result.push(numbers[i])
           }
          
        }
        console.log(result.reduce(function (a, b) {
            return a + b;
          }, 0)); // This works as expected
      }

  multiply(numbers) {
    let result2 = [];
    for (const j in numbers) {
       if (typeof numbers[j] === "number"){
        result2.push(numbers[j])
       }
      
    }
    console.log(numbers.reduce((a, b) => a * b)); //This is returning NAN inside of the multiplication result
    
    
  }

  subtract(num1, num2) {
    return num1 - num2;
  }

  divide(num1, num2) {
    return num1 / num2;
  }
 
}
  
 let values = new Calculator();
 values.add([10, undefined, -1, 10, 100]);
 values.multiply([10, 5, 6, 'a']);

null

Answer 1

尝试更改数字。reduce为result2。reduce。请参阅下面的更新代码。

null

       class Calculator {

            add(numbers) {
                let result = [];
                for (const i in numbers) {
                    if (typeof numbers[i] === "number") {
                        result.push(numbers[i])
                    }

                }
                console.log(result.reduce(function (a, b) {
                    return a + b;
                }, 0)); // This works as expected
            }

            multiply(numbers) {
                let result2 = [];
                for (const j in numbers) {
                    if (typeof numbers[j] === "number") {
                        result2.push(numbers[j])
                    }

                }
                console.log(result2.reduce((a, b) => a * b)); //This is returning NAN inside of the multiplication result


            }

            subtract(num1, num2) {
                return num1 - num2;
            }

            divide(num1, num2) {
                return num1 / num2;
            }

        }

        let values = new Calculator();
        values.add([10, undefined, -1, 10, 100]);
        values.multiply([10, 5, 6, 'a']);