主题：请教JS代码

function shqr() {
    var v1 = document.getElementById("shd1").files.length;
    if (v1 > 0) {
        show("t1");
        var result = submitAjaxForm('form1', 'afterSubmit');
    }

}
function afterSubmit(result) {
    alert(result);
    hide("t1");
    if (result == 'qrcg') {
        history.pushState(null, null, document.URL);
        window.addEventListener('popstate',
        function() {
            history.pushState(null, null, document.URL);
        });
        show('dlg5');
    } else {
        showDialog('dlg3', '错误', result);
    }
    return true;
}