data = [0,3]
data = [5,9]
data = [4,4]

如何转变为[0,1,2,3]
如何转变为[5,6,7,8,9]
如何转变为[4]

用 for 循环就可以了

let data1 = [0, 3]  
let data2 = [5, 9]  
let data3 = [4, 4]

console.log(getList(data1))
console.log(getList(data2))
console.log(getList(data3))

function getList(data) {
    let startIndex = data[0]
    let endIndex = data[1]
    let resultList = []
    for(startIndex; startIndex <= endIndex; startIndex++){
        resultList.push(startIndex)
    }
    return resultList
}

提的什么问题

const formatArray = (input = []) => {
    const arr = []
    if (Array.isArray(input)) {
        let [start, end] = input
        while (start <= end) {
            arr.push(start++)
        }
    }
    return arr
}

Array(data[1]-data[0]+1).fill('').map((t,i) => {return i+data[0]})