How to show different dropdowns by choice

I want to show different dropboxes to user by its own choice.

example;

Dropbox1;

1-> Apple 2-> Bluberry

when user choose choice 1 it`ll show

1a -> Apple Juice 1b -> Apple

when user choose choice 2 it`ll show

2a -> Blueberry Juice 2b -> Blueberry开发者_运维问答

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Whenever I have to create such a thing, I'll create a multidimensional array. For example: [ ["Blueberry", "Pie"], ["Apple", "Pie"], ["Lemon", "Pie"] ]

Then in the first dropdown I set an onchange action to a function that checks which ID is selected, if for example ID 1 is selected, I'll get the array at index 1, in this example being ["Apple", "Pie"].

Then I'll empty the second dropdown and loop through the array to generate new options and place them in the body of the second dropdown.