Require a wordpress taxonomy to be selected

Require a wordpress taxonomy to be selected

/*
 * Enqueue this function anywhere in the wordpress admin to require a category selection on the array of post types
 */
 $(function() {
	var post = document.getElementById('post'), 
		post_types = ['post'], 
		post_type = false,
		errormsg = function(str) {
		    msgdiv = document.getElementById('message');
		    if (msgdiv) {
				msgdiv.innerHTML = '<p>' + str + '</p>';
				if (!$(msgdiv).hasClass('error')) $(msgdiv).addClass('error');
			} else {
				msgdiv = document.createElement('div');
				msgdiv.id = 'message';
				msgdiv.className = 'error';
				msgdiv.innerHTML = '<p>' + str + '</p>';
				post.parentNode.insertBefore(msgdiv, post);
			}
		};

	for(var i=0; i<post_types.length; i++) {
		if ($(document.body).hasClass('post-type-'+post_types[i])) {
			post_type = post_types[i];
			break;
		}
	}

	if (post && post_type) {
		$(post).on('submit', function(e) {
			if (document.getElementById('categorychecklist') && $('#categorychecklist').find("input:checked").length < 1) 
				e.preventDefault();
				$('#categorydiv').addClass('error');
				errormsg('Please select a category');
				return;
			}
		});
	}
});