2-logical-operators-advanced-conditionals

Part II: Logical Operators & Advanced Conditionals

Note: Before getting started on these exercises, please be certain that you've read through the root README.md file in this repository.

Exercises

Basic Requirements

Logical Operators

1. Is the ! operator a unary operator, or binary operator?

2. Evaluate each of the following expressions first on a whiteboard, and then in a console:

   !(2 >= 2)
   !(4 === 4)
   !(5 !== 5)

3. Evaluate each of the following expressions first on a whiteboard, and then in a console:

   1 > 2 || 2 > 2 || 3 > 2
   5 < 5 || 75 < 74

Conditionals: else if & else

1. This guy named "Joe" keeps blacking out at the bar that your function, bouncer (from the previous module), is in charge of; thus, management has decided to add him to the "blacklist" -- modify the bouncer function from the previous section so that the person named "Joe" is rejected with an appropriate message, regardless of his age.

2. Write a function called scoreToGrade that accepts a number as a parameter and returns a string representing a letter grade corresponding to that score.

   For example, the following grades should be returned given these scores:

   • 'A' >= 90
   • 'B' >= 80
   • 'C' >= 70
   • 'D' >= 60
   • 'F' < 60

   function scoreToGrade(score) {
     // TODO: your code here
   }
   scoreToGrade(95); // => 'A'
   scoreToGrade(72); // => 'C'

3. Modify the scoreToGrade function so that it returns 'INVALID SCORE' if the score is greater than 100 or less than 0.

More Practice

1. Think of at least three activities that you enjoy doing outdoors and the range of temperatures and weather patterns (e.g sunny, windy, snowy, rainy, etc.) that are best for these activities. Write a function whatToDoOutside that accepts a temperature and condition as parameters and outputs a string of the format: "The weather is ideal for: ACTIVITY" (where ACTIVITY is an actual activity). Make sure to include an else that indicates what should be done if the conditions do not match any activities. If you're short on inspiration, here are some ideas:

   • Snow Sports: snowboarding, skiing
   • Water Sports: surfing, sailing, paddle boarding, swimming
   • Team Sports: basketball, baseball, football (American or everywhere else), etc.

2. The guessMyNumber function from the Booleans & Conditionals module (More Practice section) accepts a guess n and checks it against a random number from 0 to 5 -- if the guess n is greater than 5, output a different message indicating that the guess is out of bounds.

   • NOTE: It will be helpful to first write a randInt function that accepts a number n and computes a random integer from 0 to n; then, you can use this function in guessMyNumber.

3. Modify the scoreToGrade function so that it returns 'A+/A-' for scores of 98-100/90-92 respectively. Apply the same logic for all other letter grades.

Advanced

1. The bar that employs our bouncer function has decided to do live music on Friday and Saturday nights, and will be admitting those that are over 18 to the bar on those nights; the catch however, is that all who are 21 or older will need to be given a wristband to distinguish them from the minors. Modify your bouncer function to handle this situation.

2. You should have noticed a large amount of repetitive code when modifying scoreToGrade to accommodate + or - grades. When we do lots of repetitive things, that's a clear signal that there's a better way. Write a helper function letterGrade that accepts two arguments, letter and score, and works as follows:

   function letterGrade(letter, score) {
     // your code here
   }
   // These are examples of what a *working* function would output.
   letterGrade('A', 95); // => 'A'
   letterGrade('A', 91); // => 'A-'
   letterGrade('B', 88); // => 'B+'
   letterGrade('monkey', 160); // => 'monkey-'

   Finally, use letterGrade to remove the repetition in scoreToGrade.

3. It turns out that we can write logical and and logical or in terms of each other and logical not using De Morgan's Laws.

   • Write a function or that works like ||, but only uses ! and &&.
   • Write a function and that works like &&, but only uses ! and ||.