Select

Sometimes we have a single goroutine listening to multiple channels and want to process data in the order it comes through each channel.

A select statement is used to listen to multiple channels at the same time. It is similar to a switch statement but for channels.

select {
case i, ok := <-chInts:
	if ok {
		fmt.Println(i)
	}
case s, ok := <-chStrings:
	if ok {
		fmt.Println(s)
	}
}

The first channel with a value ready to be received will fire and its body will execute. If multiple channels are ready at the same time then one is chosen randomly. In the example above, the ok variable is a boolean. It is true while the channel is open, and false when the channel is closed by the sender.