Forgive my lack of knowledge about web-technology and web-related aspects and terminologies. One answer to this question states that The DOM standards define interfaces that are implemented by the objects from the DOM object tree in the browser.
What I'd really like to know is that, are the notion of interface, implementation objects etc here the same thing we are familiar with in Object-Oriented-Programming? In other words, is the DOM API an object-oriented API?
Any language where state and methods can coexist on data structures is object-oriented. Interfaces, classes and other features that are common to statically typed OO languages aren't what makes a language OO. Also, you may not have an interface feature in JS, but conceptually an interface is just a contract that an object must fulfill so nothing would prevent documenting such interfaces in JS.
The DOM API is definitely OO. Actually, DOM stands for Document Object Model. In other words, the DOM is an object-oriented solution to the problem of representing and interacting with HTML and XML documents.
However, that doesn't mean that it respects the fundamental OO principles like the SOLID principles.
Everything in JS is an object, so the real answer to your question is yes. But I think what you are asking is what do you typically get as responses from the DOM API when you call it, and that answer is usually a HTML element as a string. That's because the DOM is just a way for scripts to connect with a web page.
It outputs HTML elements most of the time and you can test this quite easily - just use console.log(whatever); on some HTML element you have to test.
Example:
var newOne = document.getElementById('orange-text');
console.log(newOne);
Response from DOM API (typically just whatever you had in HTML):
<p id="orange-text"">This text has an orange background because of a comparison operator</p>
Now try to output that same variable, treating as an array variable calling position zero:
var newOne = document.getElementById('orange-text')[0];
console.log(newOne);
Response will be:
undefined
The answer is undefined because the DOM isn't returning an object with positions you can iterate over.
