Edit in JSFiddle

$('.btn1').on('click',function(){
    sessionStorage.setItem('key1','value1');
    sessionStorage.setItem('key2','value2');
    for (var i = 0; i < sessionStorage.length; i++)
		alert(sessionStorage.getItem(sessionStorage.key(i)));
});

$('.clear-btn').on('click',function(){
    sessionStorage.clear();
});
<button type = "button" class = "btn1">Пробуем!</button>
<button type = "button" class = "clear-btn">Очищаем!</button>