var i, j;
for (i = 0; i < 3; i++) {
document.write("i = " + i + "<br />");
for (j = 1; j < 5; j++)
document.write("j = " + j + ", ");
document.write("<br />");
}
/*
run:
i = 0
j = 1, j = 2, j = 3, j = 4,
i = 1
j = 1, j = 2, j = 3, j = 4,
i = 2
j = 1, j = 2, j = 3, j = 4,
*/