A simple definition of recursive is

" Use function inside of function . "

Below is code for Countdown function using Recursive

function countdown(n){

 // base case use this for break loop

  if(n <= 0) {
    return []
  } else {

 // call function again
    let arr = countdown(n - 1)
    arr.unshift(n)
    return arr
  }
}

countdown(10)
// [ 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 ]

Below is code for display range of number using Recursive

function rangeOfNumbers(startNum, endNum) {

 // base case use this for break loop

 if( startNum === endNum ) {
   return [startNum]
 } else {

 // call function again

     const arr =  rangeOfNumbers(startNum, endNum - 1)
     arr.push(endNum)
     return arr
 }
}

rangeOfNumbers(1, 5)
// [ 1 , 2 , 3, 4, 5 ]