Simple javascript

I have a javascript, a php file and a html file([login to view URL]) and I want 2 javascripts. when I change the select value for f09 at [login to view URL] file, the field f11 will display as a select field with the correspondence option value being selected.(Eg : f09=1, then f11=2;f09=2 then f11=1, value is selected via [login to view URL] file). I have a new html file([login to view URL]), which is having 3 lines of f06, f07, f09, f11 and f12. What I want now is a javascript which when I change the select value for f09, the field f11 will display as a select field with the correspondence option value being selected too. My [login to view URL] file is having 3 lines, what I want is when I add lines for the [login to view URL], it shall be working even up to 500 lines, this is the 1st javascript I wanted. The 2nd javascript I want is when the f06 being input, then the f09 and f11 cannot be blank for that particular line, and when the f07 being input, then the f12 cannot be blank for that particular line. This is a validation script. However, when f06 is not being input, f09 and f11 for that particular line is not required, and when f07 is not being input, f12 for that particular line is not required. This shall be working even up to 500 lines. I want this 2 javascripts to work in Mozilla Firefox, IE, Opera, Google Chrome, Edge and Safari.