@Ankur Bawiskar ,

alert("hello");
    var start = g_form.getValue('start_date');
    var year = new GlideAjax('BT_CSR_SSR_CatalogUtils');
    year.addParam('sysparm_name', 'checkLeepyear');
    year.addParam('sysparm_date', start);
I have changes according, But still it is the same
answer alert, I'm getting has undefined and no log's