WebtextEdit executes Javascript function

I need to execute all JavaScript function.

Found what I was doing wrong:

var edit = igedit_getById("FG2100RefNo");
var editText = edit.getText();
alert(!isNaN(editText));

      

        
        
        
      

    

But this only checks and displays a message box.

I need to execute the below JavaScript:

<script language=Javascript>
  <!--
  function isNumberKey(evt)
  {
     var charCode = (evt.which) ? evt.which : event.keyCode
     if (charCode > 31 && (charCode < 48 || charCode > 57))
        return false;

     return true;
  }
  //-->

      

        
        
        
      

    

onkeypress="return isNumberKey(event)"

      

        
        
        
      

    

How can I do this using webtextedit:

var edit = igedit_getById("FG2100RefNo");
var editText = edit.getText();
function isNumberKey(evt)
{
    var charCode = (evt.which) ? evt.which : event.keyCode
    if (charCode > 31 && (charCode < 48 || charCode > 57)) return false;
    return true;
}
return isNumberKey(editText)

      

        
        
        
      

    

I only have the property value onkey

to insert the code.