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Understanding The Problem Domain Is The Hardest Part of Programming

Some of the hardest things about writing code other than Domain?

• You’re having to learn a new technology

• Learning how to name things

• Testing Code

• Debugging

• Knowing how to go about fixing issues/bugs

• Developing software that can be maintained

Problem Domains are Difficult to understand

Not often do programs recieve all of the information about a problem domain to be able to understand it. Learn how to understand The Problem Domain. When you understand the problem domain you will understand what code needs to written for it.

How can one understand the problem domain handed to them?

• make it easier-simplify it!

• improve your understanding of it, as thoroughly as possible!

Duckett JS book Chapter 3: “Object Literals” (pp.100-105)

What’s an object?

Objects group up variable and function in order to create models which represent a real world project.

objects change what variables and functins get new names

• variables become properties, properties describe what the object is

• functions become methods, methods represent tasks that have to do with the object

use hotel example on page 101

hotel = the object properties of hotel = name, rooms, booked, gym. values of properties = strings, numbers, booleans and arrays

method= function of “checkAvailability”

var naming object>{key with properties>method with function}

Creating Object using Literal Notation

the object is what is within the curly braces. The object is stored inside of a variable which can use a literal name like “hotel”. so you could view this literally as hotel object

eachekey within an object is separated from it’s value using :

Accesing object and dot notation/creating more object liters

use dot notation to access properties or methods of an object. can also use square brackets to access properties. **really good examples page 104-105

Duckett JS book Chapter 5: “Document Object Model” (pp.183-242)

DOM AKA Document Object Model Some folx call this the API

DOM isn’t a part of JS or HTML

It is used for:

• making a model of HTML page. *how browser should structure the model using DOM tree

• Accessing and changing the HTML page. DOM defines methods and properties the access necessary to update what users see in browser

• The DOM tree models the webpage, it then get’s stored in the browsers memory

Has four types of nodes, each notde is an object with methods and properties.

• document nodes represents entire page and corresponds with document object

• element nodes find the html elements/nodes to access DOM tree

• attribute nodes represent HTML Attribute

• text nodes after accessing element node, text node can be accessed. text nodes cannot have children

Really good visual on page 187

Working with DOM Tree

1. Acces elements within

2. work with the elements using text content, child elements and attribute

DOM Qeuries - method to find elements in a DOM tree. DOM queries will either return single element, *or a Node List with a collection of nodes

To return single element node:

getElementByID

querySelector

To return one or more elements as a node list

getElementsByClassName

getElementsBytag Name

querySelectorAll

page 197

use textContent, innerHTML or DOM manipulation techniques to update and access content from element node

*multiple text nodes and child elements that are related can be contained within an element node

DOM might be inconsistent in older browsers

browsers have tools for viewing DOM tree

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