How to create a global variable?

Question

JavaScript

There is an ajax request

//ajax под грузка сообщений на странице поста
        function getMessages() {
            $.ajax({
                url: "ajax/postComments.php",
                method: "POST",
                data: ({postID: <?php echo $id ?>}),
                dataType: "html",
                success: function (data) {
                    $('.author-messages-list').empty();
                    $('.author-messages-list').append(data);
                }
            });
        }
        var timer = getMessages();
        var timerPostAuthor = setInterval(function() {
            getMessages();
        }, 2000);

And it must be stopped, for this

//Останавливаем таймер на странице поста
    $(document).on('keyup change', '#posttext', function () {
        clearInterval( timerPostAuthor );
    });

But timerPostAuthor is not visible (timerPostAuthor is not defined writes to console and phpstorm)
How to make timerPostAuthor a global variable?
Full js

$(function () {

        //ajax под грузка сообщений на странице поста
        function getMessages() {
            $.ajax({
                url: "ajax/postComments.php",
                method: "POST",
                data: ({postID: <?php echo $id ?>}),
                dataType: "html",
                success: function (data) {
                    $('.author-messages-list').empty();
                    $('.author-messages-list').append(data);
                }
            });
        }
        var timer = getMessages();
        var timerPostAuthor = setInterval(function() {
            getMessages();
        }, 2000);

});

//Останавливаем таймер на странице поста
$(document).on('keyup change', '#posttext', function () {
   clearInterval( timerPostAuthor );
});

We are looking in the document because the form comes with an ajax request and this code (which is below) will not work stupidly

$('#posttext').on('change', function () {
    clearInterval(timerPostAuthor);
});

Answer 1

global variables in js like this: Global object