How does OOP affect how webpages look?

Do we have to import APIs like we do in Java? I'm a little confused on how to use them.

Can you elaborate more on APIs? Does it have anything to do with abstraction barrier, private and public classes?

Explain more on constructors and instance variables.

APIs are great and allow software components to communicate, does an update on an api affect all software using it? If an API is manipulated by a dangerous party does it affect the softwares that use the said API?

Can I say the class we are talking about here is like a collection of functions/variables that works as a part?

1. Can you clarify truck class and how it differs?

"2.var order1 = {emailAddress: key1,
              coffee: ""black with milk and an embarrassing amount of sugar"",
              size: ""short"",
              flavor: ""mocha"",
              strength: 38
              }; 
why size, flavor, strength are not in a string format?
Thank you!"


So when we're dealing with code where it asks for user input, we're always going to use square bracket notation because the key values depend on the user input?