如何仅在数组未定义的情况下对其进行压缩

Question

我需要添加多个数组在一起取决于用户的偏好一些数组可能会出现空，我如何确保数组我要Conconat是不是空

这是我失败的代码

const num1 = [12,67,100] 
const num2 = [] 
const num3 = [23,191, 58]
const num4 = [23,30]

const numbers = num1.concat(`num${Math.random() * 10}`)

Answer 1

好了，很容易理解：

constant numbers;
int randomArray = `num${Math.random() * 10}`;

if (randomArray.length > 0)
{
    numbers = num1.concat(randomArray);
}

Answer 2

根据这个答案，转换为二维数组并将其转换为单个平面数组，似乎是首选解决方案

const values = [ [12,67,100], [], [23,191, 58], [23,30] ]

const numbers = [].concat(...values)

console.log(`items count: ${numbers.length}`)

const randomNumbers = numbers.map(num => parseInt(num * Math.random()))

Answer 3

const num1 = [12, 67, 100]
const num2 = []
const num3 = [23, 191, 58]
const num4 = [23, 30]

const check = `num${Math.random() * 10}`
const numbers = num1.concat(check && check)

console.log(numbers);