<script type="text/javascript">
    function doinserttable(obj){
        textarea = document.getElementById(obj);
        var RowNum = prompt("Number of Rows", "3");
        var ColNum = prompt("Number of Columns", "2");
        if(RowNum!=null && ColNum!=null && !isNaN(RowNum) && !isNaN(ColNum)){
            var str="[table]\n";
            for(irow=0;irow<RowNum;irow++){
                str +="[tr]\n";
                for(icol=0;icol<ColNum;icol++){
                    str +="[td] [/td]\n";
                }
                str +="[/tr]\n";
            }
            str += "[/table]\n";
        }
        
        textarea.innerHTML += str;
    } 	
</script>

<a href="#" onclick="doinserttable('textarea'); return false;">اضافة جدول</a>
<textarea id="textarea"></textarea>