javaScript help needed basic stuff im afraid

im sorry this is only easy stuff for you but it would help me. if your doing programe for client base 1 and 2 and they have to enter that data and if they get it wrong you have say to try again but without a loop they have only 2 attempts. while i know this is if/else im not sure about the last bit for try again?
also var clientBase, clientbase=new, established OR var new var established...

I am doing a programe where someone has to put in 1 for being a new customer and 2 for being established. if wrong data is put in then message is try again but only twice no loop.
My problem is while i know this is if/else i dont know how to write if data is wrong try again (so last if/else.
also is var Customers, customers=new, established OR var new customers, var established customers?

would love help

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