Invite users to a slack room / group as a batch

batch-invite.js

// Instructions: Open slack, switch to the channel you want to invite people to,
// Copy and paste the entire code snippet below to the "Console" tab of your web inspector, hit "Enter".

(function () {
	var people = prompt('Paste the usernames you want to invite here and hit OK:').split(/,\s*|\s+/);
	var textArea = $('#message-input');

	var dismiss = function () {
		$(".dialog_go").click();
	}

	var nextInvite = function () {
		var person = people.pop();
		textArea.val('/invite ' + person);
		TS.view.submit();
		setTimeout(dismiss, 500); // Dismiss the confirmation popup when inviting to a private group
		if (people.length > 0) {
			setTimeout(nextInvite, 1000); // Rate limit to avoid upsetting Slack
		}
	}

	nextInvite();
})();

By looking at the script (but I am not expert) I don't think they should. Anyway I tried both and none of that worked when trying to have them added to a user group.

Deprecated!

The best practice is now described in the Web Applications StackExchange: How do I invite all team members to a new Slack channel?