Making radio buttons make a single feild required depending on selection

[Steven5E99]

Hello Everyone, 

I am trying to use 4 radio buttons, but have only two make a text field required. Here is an example:

-Class A  O (radio button)

-Class B  O (radio button)

-Class C  O (radio button)

-Class D  O (radio button)

Supportive Documentation [_________________] (Text Feild )

Only one of the options: Class A, B, C, or D can be selected. If A or B is selected, the "Supportive Documentation" field SHOULD be required. If C or D is selected, the "Supportive Documentation" field should NOT be required. 

Any help at all would be greatly appreciated.

[ls_rbls · Accepted solution]

Very quick and easy:

In the A and B radio buttons properties "Actions" tab, place the following line of script:

this.getField("Supportive Documentation").rewuired = true;

And in the C and D radio buttons use instead:

this.getField("Supportive Documentation").required = false;