[Ervin]

Можно использовать localstorage.

function createFile(str, repl) {
       var storage = (window.localStorage && window.localStorage.setItem) ? window.localStorage : null;
       
        if(storage) {
            if(!repl) {
               storage.setItem(storage.length + 1, str);
            }
            else {
               storage.setItem(storage.length, str);
            }
        }
   }


<input type="button" value="Первая кнопка" onClick="createFile(9)">
<input type="button" value="вторая кнопка" onClick="createFile(15)">
<input type="button" value="Третья кнопка" onClick="createFile(256)">