Read: 07 - Object-Oriented Programming, HTML Tables

Domain Modeling

1. Explain why we need domain modeling. Domain modeling is the process of creating a conceptual model in code for a specific problem. A model describes the various entities, their attributes and behaviors, as well as the constraints that govern the problem domain. An entity that stores data in properties and encapsulates behaviors in methods is commonly referred to as an object-oriented model.

A domain model that’s articulated well can verify and validate the understanding of a specific problem among various stakeholders. As a communication tool, it defines a vocabulary that can be used within and between both technical and business teams.

HTML Table Basics

1. Why should tables not be used for page layouts? HTML tables should be used for tabular data — this is what they are designed for. Unfortunately, a lot of people used to use HTML tables to lay out web pages, e.g. one row to contain the header, one row to contain the content columns, one row to contain the footer, etc. You can find more details and an example at Page Layouts in our Accessibility Learning Module. This was commonly used because CSS support across browsers used to be terrible; table layouts are much less common nowadays, but you might still see them in some corners of the web.

In short, using tables for layout rather than CSS layout techniques is a bad idea. The main reasons are as follows:

Layout tables reduce accessibility for visually impaired users: screen readers, used by blind people, interpret the tags that exist in an HTML page and read out the contents to the user. Because tables are not the right tool for layout, and the markup is more complex than with CSS layout techniques, the screen readers’ output will be confusing to their users. Tables produce tag soup: As mentioned above, table layouts generally involve more complex markup structures than proper layout techniques. This can result in the code being harder to write, maintain, and debug. Tables are not automatically responsive: When you use proper layout containers (such as <header>, <section>, <article>, or <div>), their width defaults to 100% of their parent element. Tables on the other hand are sized according to their content by default, so extra measures are needed to get table layout styling to effectively work across a variety of devices.

1. List and describe 3 different semantic HTML elements used in an HTML <table>. The <tbody> HTML element encapsulates a set of table rows (<tr> elements), indicating that they comprise the body of the table (<table>). The <colgroup> HTML element defines a group of columns within a table. The <caption> HTML element specifies the caption (or title) of a table.

Introducing Constructors

1. What is a constructor and what are some advantages to using it? Using object literals is fine when you only need to create one object, but if you have to create more than one, as in the previous section, they’re seriously inadequate. We have to write out the same code for every object we create, and if we want to change some properties of the object - like adding a height property - then we have to remember to update every object.

We would like a way to define the “shape” of an object — the set of methods and the properties it can have — and then create as many objects as we like, just updating the values for the properties that are different.

1. How does the term this differ when used in an object literal versus when used in a constructor? You use constructors over object literals when you need to create more than one object.