javascript - JS 数组中所有项相乘

Question

我是 JavaScript 新手，正在闲逛以真正理解基础知识。现在我尝试做一个计算器。一个非常基本的运算，可以加、减、除、乘。我已经让它与此代码一起使用(仅显示乘法:

var multiply = function () {
var numbers = prompt("How many numbers do you want to multiply?","At least 2, max 4");
        numbers = Number(numbers);
        switch (numbers){
            case 2:
                num1 = prompt("Your first number: ");
                num2 = prompt("Your second number: ");
                ans = Number(num1) * Number(num2);
                alert(num1 + " * " +  num2 + " = " + ans);
                break;
            case 3:
                num1 = Number(prompt("Your first number: "));
                num2 = Number(prompt("Your second number: "));
                num3 = Number(prompt("Your third number: "));
                ans = Number(num1) * Number(num2) * Number(num3);
                alert(num1 + " * " +  num2 + " * " + num3 + " = " + ans);
                break;
            case 4:
                num1 = Number(prompt("Your first number: "));
                num2 = Number(prompt("Your second number: "));
                num3 = Number(prompt("Your third number: "));
                num4 = Number(prompt("Your fourth number: "));
                ans = Number(num1) * Number(num2) * Number(num3) * Number(num4);
                alert(num1 + " * " +  num2 + " * " + num3 + " * " + num4 + " = " + ans);
                break;
            default:
                alert("Not valid");
                break;
        }
};
multiply();

我的问题是，当涉及到用户可以相乘的数字数量时，我非常有限。为每个可能的数量制作一个开关盒需要一段时间，所以我想到了这个:

    var multiply = function () {
        var numbers = [];
        var ans = 0;
        var times = prompt("How many numbers do you want to multiply?");
        for(var i = 0; i<times; i++){
            Number(numbers.push(prompt("Please, enter one of your numbers")));
        }
        alert(ans);
    };
    multiply();

所以，我的问题是:如何使“ans”等于数组“numbers”中的每个元素彼此相乘？

Answer 1

您可以使用reduce函数:

[1, 2, 3, 4].reduce(function(a, b) {
  return a * b;
}); // it return 24

顺便说一句。在循环中，您应该以这种方式推送到数组:

for(var i = 0; i<times; i++){
  numbers.push(Number(prompt("Please, enter one of your numbers")));
}