Current year subtract DOB year in YYYY format

Hi All,

Could you please help me out figuring out the javascript for arriving below-desired value.

As I give DOB year in YYYY Format in Text1 Field, then Text2 Field should display Current Year Minus DOB Year. If I give 1990 as DOB, then the result must be 33 Years.

Hope I have explained my problem and look forward to receiving the solution.