How to restrict the amount of categories/post tags/terms for a post type post

Question

I'm in need of a solution that allows me to restrict the user/author to only use maximum of two categories per new post. One post can only have one or two categories.

The only similar solution that I have found is when you make the categories as radio buttons instead of check boxes. But that will restrict the user to choose only one category. Only one category per post

Any idea have to solve this?

Answer 1

Thanks the the replies. I solved my problem with jQuery.

Here is the code:

jQuery(document).ready(function ($) {
$("#category-tabs li.hide-if-no-js").hide(); //Hides Most Used tab

$("#category-all input:checkbox").change(function () {
    var max = 2; // Max allowed cats
    var count = $("#category-all input:checked").length; //counts selected cats
    if (count > max) {
        $(this).prop("checked", "");
        alert('You are only allowed to select ' + max + ' categories.'); //alert message when user tries to select a third cat
    }
  });

});