here some answers :
making the problem domain so trivial make it easily understood,like I am able to make both teaching and learning easier.
because you can’t really see what you are trying to build very clearly.
If understanding the problem domain is the hardest part of programming and you want to make programming easier, you can do one of two things:
Programming is easy if you understand the problem domain. You can often make the problem domain easier by cutting out cases and narrowing your focus to a particular part of the problem.
What I mean by this is that it is often beneficial to take a part of the problem and fully understand that part before expanding the problem domain.
Objects group together a set of variables and functions to create a model of a something you would recognize from the real world. In an object, variables and functions take on new names.
See the example below
The Document Object Model (DOM) specifies how browsers should create a model of an HTML page and how JavaScript can access and update the contents of a web page while it is in the browser window.
The DOM is neither part of HTML, nor part of JavaScript; it is a separate set of rules. It is implemented by all major browser makers, and covers two primary areas:
As a browser loads a web page, it creates a model of that page. The model is called a DOM tree, and it is stored in the browsers’ memory.
It consists of four main types of nodes :
Accessing and updating the DOM tree involves two steps:
get El ementByi d () allows you to select a single element node by specifying the value of its id attribute.
When a DOM method can return more than one element, it returns a Nodelist (even if it only finds one matching element).
The get El ementsByTagName () method allows you to select elements using their tag name.
When you select a text node, you can retrieve or amend the content of it using the node Va 1 ue property.
To work with text in an element, first the element node is accessed and then its text node.
The textContent property allows you to collect or update just the text that is in the containing element (and its children).
there are two different ways to fdo that :
The innerHtml properity.
DOM manipulation.