What is DOM? DOM is the abbreviation as what stands for Document Object Model in JavaScript . Imagine DOM as your project agenda table where all the information (data) is placed on / in . The information is nothing else but HTML object-like Elements representation called HTMLCollection or HTML array-like Elements abstraction representation called Nodelist . Each has has pros and cons, but overall – Nodelist is much more flexible in terms of properties and methods it has relatively compared with HTMLCollection itself . When it comes about either : HTMLCollection or Nodelist, they have state of being live or static . HTMLCollection is always live . Being live means every time you add a something to it, it will maintain up-to-date length property of it . However Nodelist is usually static, but there some exclusions . For more about HTMLCollection vs. (static) Nodelist & how to preserve the Nodelist state of being live, please read the articles provided down below in the reference section .

---

References to the articles :
HTMLCollection vs. Nodelist
static (non-live) vs. live Nodelist