Hello, I use a form on my website. This form contains content that can only be selected once.
I would like to create some sort of "queue" when there is more than one visitor on the page.
So for example 2 visitors: visitor 1 -> fill in the form. visitor 2 -> gets popup with "please wait" visitor 1 -> sends the form. system processes data from form. visitor 2 -> make popup invisible and show form.
Or another option would be to check if someone else has checked the checkbox yet and give a message if someone has checked this yet.
Well, as you didn't provide any code I will just give you my humble thoughts on this.
First of all: May I ask why? This sounds like a horrible user experience...
If you really want to do it anyways, here's what you need: AJAX or jQuery to provide the live feedback popup you mentioned. For the visitor count caching part there are obviously many ways to do it like using scripts of any kind or even some file or database based solution. From that point on you just go with your favorite web language and code the main queue logic, I would recommend PHP with a breeze of JavaScript.
I hope this was at least a little bit helpful.
Kind regards