how to change dropdowns values based on a selection of another dropdown using jquery

Question

I have my first dropdown with 2 selections: Standard Glass and Tempered glass. I have another dropdown where the user can select the width of the glass.

My problem:

Answer 1

have a look at this code

 select
  Standard/Annealed Glass Width
    Tempered Glass Width





    
        19
      20
      21
    
    
        6
        7
        8