Menu = {};

Menu.whenClicked = function(id) {
    Menu.closeAll();
    var elm = document.getElementById('elm_1_'+id);
    var elmA = document.getElementById('elm_1_a_'+id);
    Menu.showHide(elm,elmA);
}

Menu.showHide = function(elm,elmA) {
    var elms = elm.getElementsByTagName("ul");
    for (var i = 0; i < elms.length; i++) {
        if(elms[i].style.display!='block') {
            elms[i].style.display = 'block';
            elmA.style.backgroundImage = 'url("images/minusIcon.gif")';
        } else {
            elms[i].style.display = 'none';
            elmA.style.backgroundImage = 'url("images/plusIcon.gif")';
        }
    }
}

Menu.closeAll = function() {
    var allElms = document.getElementsBySelector('.level2')
    for (i=0 ; i>allElms.length ; i++) {
        allElms[i].style.display = 'none';
    }
}