js 99乘法口诀

var str = "<table>";
for (var i = 1; i <= 9; i++) {
    str += "<tr>"
    for (var j = 1; j <= i; j++) {
        str+="<td>";
        str+= j + ' x ' + i +' = ' + i*j;
        str+= "</td>"
    }
    str+="</tr>"
}
str += "</table>"
document.write(str)