let arr = [1,2,3,4,5]
	

	

		let index = 0
	

	

		function fn(arr, cb) {
	

	

		 console.log(index)
	

	

		 if (index < arr.length) {
	

	

		 index++
	

	

		 fn(arr, cb)
	

	

		}
	

	

		}
	

	

		fn(arr, function (data) {
	

	

		 console.log(data)
	

	

		})