Can anyone show me how to rewrite this so that instead of using forms to input rows and columns. You enter the rows and columns using prompt("");

Code:
<html>
<head>

<script type="text/javascript">

function newTable(form)//begins function
{
    var rows = Number(form.rows.value);//number function converts object values to their numbers
    var cols = Number(form.columns.value);//number function converts object values to their numbers

    var tbl = document.createElement("table");//createElement is defining container
    var tableBody = document.createElement("tableBody");
    tbl.className = "table";//asigning className class for css
	
	if (rows < 13 && cols < 13) {//Keeps the rows and columns between 1 and 12
    for ( var r = 1; r < rows; ++r )//for loop that builds rows
    {
        var row = document.createElement("tr");//Defining container
        for ( var c = 1; c < cols; ++c )//for loop that builds columns
        {
            var col = document.createElement("td");//Defining container
            col.innerHTML = "R"+r+",C"+c;//innerHTML adds inner content in each box
            row.appendChild(col);//apendChild allows us to enter text inside container col
        }
        tableBody.appendChild(row);//allows us to enter text inside container row
    }
    tbl.appendChild(tableBody);//allows us to enter text in container tableBody
    document.getElementById("columns").appendChild( tbl );//connects form input to container named table
}//end if statement\
else{
	alert("\t\t\t\tError!\n\n You can only enter a number between 1 and 12\n \t\t\tPlease Try Again");//Displays if anything outside of 1-12 conditions is inputted.

	}//end if

}//end function
</script>
<link href="part2.css" rel="stylesheet" type="text/css">
</head>
<body>
<form>
  How many rows?
  <input name="rows"/>
  <br/>
  How many columns?
  <input name="columns"/>
  <br/>
  <input type="button" value="Create table" onClick="newTable(this.form);"/>
</form>
<div id="columns"></div>
</body>
</html>