Some extra JavaScript practice

JavaScript-practice.md

Important note

Use Replit or write code in a local JS file to complete these challenges. JS Bin doesn't handle callbacks well (it throws SyntaxError: Unexpected token { even though the code works elsewhere), and Code Pen has a finnicky console: https://repl.it/languages/nodejs

For a version of these questions with hints, use this gist: https://gist.github.com/SnoopSqueak/26824b4bde4071f967100ae3f9628798

Conditionals and operators

1. Write a function getIsWordOdd that takes in a string and returns true if the word contains an odd number of characters or false if the word contains an even number of characters.

Sample calls:

console.log(getIsWordOdd("Learn")); // should log true
console.log(getIsWordOdd("JavaScript")); // should log false
console.log(getIsWordOdd("Have Fun!")); // should log true

2. Write a function setLightColor that takes in a string representing the color to set the light to. The function should log "Set light color to " followed by the given color. If the color is "yellow" or "orange", the function should also log "Warning!". If the color is "red", the function should log "Danger!!!". If the color is your favorite color, the function should also log "Hey, that's my favorite color!"

Sample calls where the favorite color is "blue":

setLightColor("green"); // "Set light color to green."
setLightColor("blue"); // "Set light color to blue." "Hey, that's my favorite color!"
setLightColor("yellow"); // "Set light color to yellow." "Warning!"

Sample call where the favorite color is "red":

setLightColor("red"); // "Set light color to red." "Danger!!!" "Hey, that's my favorite color!"

Loops, arrays, and objects

3. Write a function isBinary that takes in a string and returns true if the string contains only 1s and 0s, or false otherwise.

Sample calls:

console.log(isBinary("101")); // true
console.log(isBinary("one zero one")); // false
console.log(isBinary("10010101001111101")); // true
console.log(isBinary("10 01 10")); // false
console.log(isBinary("")); // true

4. Write a function printAnimals that iterates over a given object containing multiple other objects, each representing an animal, and prints out the animal's name and adoption status.

This is the input data:

const animals={beta:{species:"dog",weight:12,sex:"male",name:"Beta",adopted:true},spartacus:{species:"dog",weight:10,sex:"male",name:"Spartacus",adopted:true},rita:{species:"dog",weight:15,sex:"female",name:"Rita",adopted:false},dodger:{species:"dog",weight:13,sex:"male",name:"Dodger",adopted:false},oliver:{species:"cat",weight:9,sex:"male",name:"Oliver",adopted:false},yzma:{species:"cat",weight:10,sex:"female",name:"Yzma",adopted:true},kronk:{species:"cat",weight:11,sex:"male",name:"Kronk",adopted:true}};

Sample call:

printAnimals(animals);

/* expected output:

"Beta is adopted."
"Spartacus is adopted."
"Rita is not adopted."
"Dodger is not adopted."
"Oliver is not adopted."
"Yzma is adopted."
"Kronk is adopted."

end of expected output */

Callbacks and recursion

5. Write a function doIfAllowed that takes in two parameters: a string representing a secret phrase, and a function to execute if the secret phrase is the correct phrase. If the given phrase is not the correct phrase, the function should log "You are not allowed to do that." The secret phrase is up to you.

Sample calls, assuming the secret phrase is "let me in":

doIfAllowed("let me in", () => console.log("I'm in!")); // should log "I'm in!"
doIfAllowed("idk", () => console.log("No dice.")); // should log "You are not allowed to do that."
function countToTen() {
  for (var i = 0; i < 10; i++) {
    console.log(i + 1);
  }
}
doIfAllowed("not allowed", countToTen); // should log "You are not allowed to do that."
doIfAllowed("let me in", countToTen); // should log the numbers 1-10.

6. Write a function tellStory that takes in an array of strings representing animal names and logs a story about each animal. The first animal can't sleep, so their mother tells them a story about the next animal; that animal can't sleep, so that animal's mother tells them a story about the next animal; etc. The last animal in the array does fall asleep, and after that the other animals can also fall asleep. You don't have to worry about indentation if you don't want to.

Sample call:

tellStory(["child", "frog", "bear", "weasel"]);
/* sample output

"A child couldn't sleep, so her mother told a story about a little frog,"
" who couldn't sleep, so the frog's mother told a story about a little bear,"
"   who couldn't sleep, so the bear's mother told a story about a little weasel,"
"     ...who fell asleep."
"   ...and the little bear fell asleep;"
" ...and the little frog fell asleep;"
"...and the little child fell asleep;"

end of sample output */

Classes and subclasses

7. Write a class called Rectangle that takes in a width and a height. Give it an area function that returns the product of width and height.

Write a class called Square that extends Rectangle and only takes in length. Since a square is a rectangle with all sides the same length, it can pass in that length for width and height.

Sample calls:

console.log(new Rectangle(10, 5).area()); // should log 50
console.log(new Rectangle(3, 9).area()); // should log 27
console.log(new Square(5).area()); // should log 25
console.log(new Square(10).area()); // should log 100