hyper-n0va/sb-js-boolean

Boolean Logic Exercises

Part I

Write down what the following statements will return. Try to figure this out before putting the commands in the chrome console.

1. 2 == “2”;
   • true
2. 2 === 2;
   • true
3. 10 % 3;
   • 1
4. 10 % 3 === 1;
   • true
5. true && false;
   • false
6. false || true;
   • true
7. true || false;
   • true

Part II

Answer the following questions about this code block:

let isLearning = true;
if(isLearning){
  console.log("Keep it up!");
} else {
  console.log("Pretty sure you are learning....");
}

1. What should the above code console.log?
   • console.log will output "Keep it up!" because isLearning is truthy.
2. Why do we not need to specify if(isLearning === true)? Why does if(isLearning) work on its own?
   • true is truthy and is what if statements check for.

let firstVariable;
let secondVariable = "";
let thirdVariable = 1;
let secretMessage = "Shh!";

if(firstVariable){
  console.log("first");
} else if(firstVariable || secondVariable){
  console.log("second");
} else if(firstVariable || thirdVariable){
  console.log("third");
} else {
  console.log("fourth");
}

1. What should the above code console.log? Why?

   • third
   • firstVariable is falsey and is skipped, secondVariable is also falsey and the first else if is skipped. thirdVariable is truthy, so "third" is printed. The else is skipped because the condition was met.

2. What is the value of firstVariable when it is initialized?

   • undefined

3. Is the value of firstVariable a “truthy” value? Why?

   • No, it is falsey. firstVariable is undefined

4. Is the value of secondVariable a “truthy” value? Why?

   • No, it is falsey. Empty strings are falsey.

5. Is the value of thirdVariable a “truthy” value? Why?

   • Yes, it is. Any number except 0 is truthy.

Part III

1. Research  here

   Math.random

   Write an if statement that console.log’s “Over 0.5” if Math.random returns a number greater than 0.5.

   Otherwise console.log “Under 0.5”.

   let rand = Math.random();
   if (rand > 0.5) {
       console.log("Over 0.5");
   } else {
       console.log("Under 0.5");
   }

2. What is a falsey value? List all the falsey values in JavaScript.

   • A falsey value is a value that is false in a conditional statement.
   • undefined, null, 0, "" (any empty string), NaN, and false.