JavaScript __dopostback gets called by clicking anywhere on the page

I have an html table in my asp.net application. When a td element is clicked, I store td element id in a hidden field using JavaScript. After that, I am forcing __dopostback from JavaScript to use the hidden field value in code behind.

Jan Feb

$('.window td').on('click', function () {
        var idName = this.id;
        var selectedid = idName.substring(1);
        console.log(selectedid);
        $('#hidden').val(selectedid);
        _doPostBack(idName , '');
});

Now when I click on anywhere in the page, __doPostBack gets called. But I want it to be called only when td element is clicked.

How do I prevent __doPostBack from getting called when user clicks anywhere else?