How to maintain the order of GoRoutines using sync.WaitGroup And Channel

here’s the code

package main

import (
 "math/rand"
 "sync"
 "time"
 "fmt"
)

func main() {
 var wg sync.WaitGroup
 total := 1000
 var channels []chan int

 for i := 1; i <= total; i++ {
  wg.Add(1)
  ch := make(chan int)
  channels = append(channels, ch)
  go func(idx int, chn chan<- int, wg *sync.WaitGroup) {
   defer wg.Done()
   var randomizer = rand.New(rand.NewSource(time.Now().UTC().UnixNano()))

   time.Sleep(time.Duration(randomizer.Intn(500)) * time.Microsecond)
   chn <- idx
  }(i, ch, &wg)
 }
 for _, ch := range channels {
  fmt.Println(<-ch)
  close(ch)
 }

 wg.Wait()
}

The results is :

1
2
3
4
5
...
...
989
990
991
992
993
994
995
996
997
998
999
1000