let a = Array.from(3)
console.log(a) //length 為3的數(shù)組 a[0]? =?undefined
let b = Array.of(3)
console.log(b)//length為1的數(shù)組 b[0]=3
let a = Array.from(3)
console.log(a) //length 為3的數(shù)組 a[0]? =?undefined
let b = Array.of(3)
console.log(b)//length為1的數(shù)組 b[0]=3