Functions Lab

Learning Goals

• Define functions using function declaration
• Define functions using function expression
• Define functions with parameters
• Define functions with default arguments

Introduction

Functions are are important concept in not just JavaScript, but programming in general. They open up what you can do with code and what kind of problems you can solve. As such, it's important we get the basics down! This lab will have you practicing basic function definition, as well as a small challenge at the end combining two concepts we've learned together: if...else statements and, of course, functions.

Getting Started

Fork and clone this lesson into your local environment. Navigate into its directory in the terminal, then run code . to open the files in Visual Studio Code. Do your work in the given index.js file.

Install all the dependencies with npm install to ensure you can test your work as you go with npm test.

The Problems

Define a function called saturdayFun using function declaration:

• It has one parameter that expects a string
• It uses a default argument, 'roller-skate' when no argument are passed.
  • It allows the default argument to be overridden.
• It returns a string like "This Saturday, I want to ...!" where the ... should be filled in with whatever is passed in as the first argument.

Define a function called mondayWork using function declaration:

• It has one parameter that expects a string
• It uses a default argument, 'go to the office' when no arguments are passed.
  • It allows the default argument to be overridden.
• It returns a string like "This Monday, I will ..." where the ... should be filled in with whatever is passed in as the first argument.

Define a function called wednesdaySleep using a function expression:

• It has two parameters, both expect a string
• It uses a default argument for both parameters when no arguments are passed.
  • First parameter default: 'very tired'.
  • Second parameter default: 'early'.
  • It allows both deafult arguments to be overridden.
• It returns a string like "Every Wednesday, I am ... after work. I will usually go to bed ..." where the ...'s should be filled in with the first and second parameter respectively.

Define a function called favoriteDay using your function definition method of choice:

• It has one parameter that expects a string

• It use a default argument, 'Saturday' when no arguments are passed.

  • It allows the default argument to be overridden.

• It should return a different string based on what is passed in as an argument.

  • If the argument passed in is a weekday, the string should say "I actually prefer weekdays, specifically ..."
  • If the argument passed in is a weekend, the string shoud say "Who doesn't love the weekend! I especially love ..."
  • In both cases, the ... should be filled in with whatever is passed in as the first argument.

  BONUS: Sometimes, you never know what user's are going to pass in as arguments. What if a user puts in an animal instead of a day, for example? Neither of our sentences would make much sense. Try accounting for that by returning a third different string that says something like "Error: That's not a day of the week, try again!"

Conclusion

In this lab, you practiced function fundamentals like function declaration. We've also seen that there are more you can do inside functions than just a single return line or console log. With just these basics in hand, you're ready to tackle more complex problems with JavaScript!