How to implement dynamic update of dropdownlist?

Question

ASP.NET

Good afternoon!
I am working on creating a website for a translation company.
I use ASP.NET MVC 5, the question is this:
the site has a questionnaire for the translator, in which he selects the languages ​​​​that he owns, and below he must determine the language pairs of the translation.
It should look something like this (roughly):

Picture

in the first drop-down list (first language) and in the second (second language), only those languages ​​that the user has selected should appear, and if the user changes languages, the drop-down list is automatically updated as well.
How to implement this, please help.

Answer 1

Use ajax. On the "onchange" event, send an ajax request to the controller which will return json . You parse the resulting json on the client side and update the DOM.