Making fields visible based on value of feild 1 and feild 2

[PD369]

I have feild A and feild B both drop down feilds I want to display Feild C Text feild only if I have perticular selections from both feilds A and B.

Any suggestions please and where should I write the script?

Thank You in advance.

[try67]

You should use the Calculate event of the third field.

[PD369]

Thank you I will try. 
 Any suggestion on article or answer that I can look into?

[try67]

You can use something like this code:

event.target.display = (this.getField("Field A").valueAsString = "123" && this.getField("Field B").valueAsString = "456") ? display.visible : display.hidden;

You'll need to adjust the field names and values, of course.

[PD369]

I tried document level script but Did not work as I need to apply same logic to multiple feilds.Any idea why ? 

[Nesa Nurani]

We can't assist you effectively without a clear understanding of what you're trying to achieve. Please explain your needs in as much detail as possible.

Post the script you tried.