推荐(减少默认值)

Array.prototype.reduce 可用于遍历数组，将当前元素值添加到先前元素值的总和中.

Recommended (reduce with default value)

Array.prototype.reduce can be used to iterate through the array, adding the current element value to the sum of the previous element values.

console.log(
  [1, 2, 3, 4].reduce((a, b) => a + b, 0)
)
console.log(
  [].reduce((a, b) => a + b, 0)
)

你得到一个 TypeError

You get a TypeError

console.log(
  [].reduce((a, b) => a + b)
)

console.log(
  [1,2,3].reduce(function(acc, val) { return acc + val; }, 0)
)

console.log(
  [].reduce(function(acc, val) { return acc + val; }, 0)
)

如果非数字是可能的输入，您可能想要处理它?

If non-numbers are possible inputs, you may want to handle that?

console.log(
  ["hi", 1, 2, "frog"].reduce((a, b) => a + b)
)

let numOr0 = n => isNaN(n) ? 0 : n

console.log(
  ["hi", 1, 2, "frog"].reduce((a, b) => 
    numOr0(a) + numOr0(b))
)

我们可以使用eval来执行JavaScript 代码的字符串表示形式.使用 Array.prototype.join 函数将数组转换为字符串，我们将 [1,2,3] 更改为1+2+3"，计算结果为 6.

We can use eval to execute a string representation of JavaScript code. Using the Array.prototype.join function to convert the array to a string, we change [1,2,3] into "1+2+3", which evaluates to 6.

console.log(
  eval([1,2,3].join('+'))
)

//This way is dangerous if the array is built
// from user input as it may be exploited eg: 

eval([1,"2;alert('Malicious code!')"].join('+'))

当然，显示警报并不是最糟糕的事情.我包含此内容的唯一原因是回答 Ortund 的问题，因为我认为它没有得到澄清.

Of course displaying an alert isn't the worst thing that could happen. The only reason I have included this is as an answer Ortund's question as I do not think it was clarified.