<script>
                let n = prompt("enter number", "");
                let col,row;
                for (row = 1; row <= n; row++){
                    for (space = 1; space <= (n-row); space++){
                        document.write("&nbsp");
                    }
                    for(col = 1; col <= row; col++)
                    {
                       document.write ("*" + " ");
                    }
                    document.write("<br>");
                }

                for (row = 1; row <= n; row++){
                    for (space = n; space >= (n-row); space--){
                        document.write("&nbsp");
                    }
                    for(col = n-1; col >= row; col--)
                    {
                       document.write ("*" + " ");
                    }
                    document.write("<br>");
                }
            </script>