I have a form with a dropdown that when changed kicks off a javascript alert mes

Building on Rayudu's comment, consider whether the utility gained from having dynamic instructions outweighs the utility of mobile-enablement (for many customers it does not). If you decide that it does not, two JS-free design alternatives for you:
1) Make the instructions "dumber". Example instruction text: "If Option 1 is selected in Field 1 above, then ABC, otherwise, XYZ.
2) If there are too many conditions that affect the instruction text to take the above approach, then break the single form into two chained forms. Use the displayvalue() expression to display the instructions the correspond to the value selected in the first form's dropdown.

Building on Rayudu's comment, consider whether the utility gained from having dynamic instructions outweighs the utility of mobile-enablement (for many customers it does not). If you decide that it does not, two JS-free design alternatives for you:
1) Make the instructions "dumber". Example instruction text: "If Option 1 is selected in Field 1 above, then ABC, otherwise, XYZ.
2) If there are too many conditions that affect the instruction text to take the above approach, then break the single form into two chained forms. Use the displayvalue() expression to display the instructions the correspond to the value selected in the first form's dropdown.