CSci 4651 Lab 5: Javascript prototype inheritance.

Due Friday, April 29th at 11:59pm (by e-mail)

Work in pairs or groups of three on this lab.

Resources:

• Javascript "this" reference
• Prototype-based inheritance
• Date object

You will be running Javascript in a browser, as shown in the in-class example (see the page source code). Use Ctrl-Shift-I in Chrome to open Javascript console (click on the console tab). Use console.log to write to the console, do not use document.write. The console will also display errors (if any).

Lab task (25 points)

Please explore the following topics, answer the questions below, and submit the code that you wrote in order to answer these questions. Use the above resources.

• What is the "this" reference? Print it in a global context, then inside an object method. Are they the same?
• How do you print all object's properties names and values?
• What is Object.getPrototypeOf? Try it on a few different objects: functions, arrays, date object. Be careful: numbers and strings might be primitives, thus wouldn't have a prototype. This behavior may vary from one browser to another.
• What is Object.create? How is it used?
• What does a keyword "new" mean? What happens if I run arbitrary function with "new" in front of it? Use Javascript console and console.log to determine it.
Javascript uses prototype-based inheritance. What is it? How is it different from class-based inheritance? Show concrete examples.
• What are Javascript classes? How is the inheritance different from class-based inheritance, even when classes are present?

CSci 4651 course web site.