Getting all fields from Form.

I am using below cde but its not working pls some one help me.

function getFieldListFromTab(tabId)
{
    var fieldList = new Array();

    var tab = Xrm.Page.ui.tabs.get(tabId);

    tab.sections.forEach(function (section, sectionIndex)
    {
        section.controls.forEach(function (control, controlIndex)
        {
            var attribute = control.getAttribute();

            if (attribute != null)
            {
                fieldList.push(attribute.getName());
            }
        });
    });

    return fieldList;
}