[Javascript] Globalscope ofzo

<html>
    <head>
        <script src="jquery.js" type="text/javascript"></script>
        <style>
        #blokje
             {
             position:fixed;
             top:30px;
             right:50px;
             }
        #blokje2
             {
             position:fixed;
             top:30px;
             left:50px;
             }
        </style>

        <script type="text/javascript">
            function increase()
                {
                    i = i++;
                }
            function verander(var1,var2)
                {
                    //var ttt = setInterval(document.getElementById("blokje").style="top:50px;";;, 2500);
                    //var test = document.getElementById("blokje").style;
                    //document.write(test);
                    test = $(blokje).css("top");
                    test2 = parseInt(test);
                    var4 = var1 * 1000;
                    var3 = var4 / var2;
                    window.alert(var3);
                    i = 0;
                    ttt = setInterval(increase(), var3);
                    while(i<=var2)
                        {
                            window.alert(i);
                            test3 = test2 + i;
                            document.getElementById("blokje").style="top:"+test3+"px;";
                        }
                        clearInterval(ttt);
                    // document.getElementById("blokje").style="top:10px;";
                    
                }
        </script>
    </head>
    <body>
        <img id="blokje" src="block.png" alt="blokje"/>
        <img id="blokje2" SRC="block.png" onClick="verander(5,50)" alt="verander"/>
    </body>
</html>