输入1,2,3,5,7,8,10 输出 1~3,5,7~8,10

解释：连续的数一头一尾加“~”，单独的数单独输出

let arra = [1, 2, 3, 5, 7, 8, 10]
function aa (arr) {
  let res1 = []
  let pre = arr[0]
  let next = arr[0]
  let j=0
  return function () {
    for (let i = 0; i < arr.length; i++) {
      if (arr[i] + 1 == arr[i + 1]) {
        next = arr[i + 1]
      }
      else {
        res1[j]=(pre == next?arr[i]: pre + '~' + next)
        pre = next = arr[i + 1] + ""
        j++
      }
    }
    console.log(res1.toString())
  }
}
aa(arra)()