How to call a custom javascript function from webi cell?

Hi all, I'm trying to insert a javascript function into a webi cell, but I don't know how to call and declare a javascript custom function on webi.

This is my code:

="<a TITLE='Search for LittleCode' onClick=\"javascript:myfunction();return false;\" style=\"cursor:pointer\"><img src=\"/images_ses/LittleCode_2.png\" /></a>"

and myfunction() is:

function myfunction(){

  var doc = document.getElementById('Report').contentWindow.document;

  var the_rows = doc.getElementsByTagName('tr');

  var values_array = [];

  var idPost;

  for (var a = 0; a < the_rows.length; a++)

  {

    var col = the_rows[a].getElementsByTagName('td');

    for (var b = 0; b < col.length; b++)

    {

    var div1 = col[b].getElementsByTagName('div');

    for (var c = 0; c < div1.length; c++)

      {

        var div2 = div1[c].getElementsByTagName('div');

        for (var d = 0; d < div2.length; d++)

        {

          var dspan = div2[d].getElementsByTagName('span');

          for (var e = 0; e < dspan.length; e++)

          {

          ..................

}

I need to create a .js file and call this? How can I call a custom javascript function?