How can I determine the zipcode for a given State and city?

Please help me find solution for it in angular ionic.
I have a reactive form for registration where I want to allow user to enter a valid zip code based on the selection he made for state and city.
I have searched for it but not able to find solution. Mostly people were asking for the reverse of it which is to get state and city based on zip code but i need zip code based on state and city. Any help would be appreciated.

@rapropos please look into it.

Have you even googled correctly for your question? This has been asked many times and there are plenty of answers out there instead of demanding someone look into it for you. It’s not that hard to do.

@mikrochipkid i exactly searched this question but got the reverse of it. you seem to have seen some solutions for it can you please share that link ?