tawnyblvd / callback_assignment

Function Callbacks Assignment, Unit 1 Week 4

Callback Exercises

Question One

Write a function that takes in a callback and calls the callback

Input:
function() { console.log("Hello!") }

Output:
Logs "Hello!" to the console

Question Two

Write a function that takes in a callback and a boolean. If the boolean is true, call the callback, otherwise log "Ignoring the callback" to the console.

Input:
() => console.log("")

Question Three

Write a function that take in a number and two callbacks. It should apply the first callback to the number, then the second callback, then return the result

Input: 4, (num) => num + 3, (num) => num * 2

Output: 14

Question Four

You are given the following functions:

function conservativeSpender(balance)  {
  return balance > 100
}

function liberalSpender(balance) {
  return balance > 10
}

function horribleSaver (balance) {
  return balance > 0
}

Write a function shouldIBuyThis that takes in a balance and a callback (one of the above functions). The function should return either "Sure! I've got the money!" or "Nope! Gotta keep my savings up!"

console.log(shouldIBuyThis(20, horribleSaver))
// logs: "Sure! I've got the money!"
console.log(shouldIBuyThis(20, liberalSpender))
// logs: "Sure! I've got the money!"
console.log(shouldIBuyThis(20, conservativeSpender))
// logs:  "Nope! Gotta keep my savings up!"
console.log(shouldIBuyThis(101, conservativeSpender))
// logs: "Sure! I've got the money!"

Question Five

a. Write a function forEachElem that takes in an array and a callback. Call the callback on each element in the array.

Input: [1,4,5,6], (elem) => console.log("$" + elem)

Output:
Logs the following to the console:
1
4
5
6

b. Create a function logEachElem that takes an array as an argument logs every element in the input array. Use forEachElem inside the body of your function.

Input: [1,2,34]

Output:
Logs the following to the console:
1
2
34

c. Create a function logArrTypes that uses the forEachElem method to log each array element followed by its type.

Input: [1,"Hi", true, {color: "green"}]

Output:
Logs the following to the console:
1 is a number
Hi is a string
true is a boolean
[object Object] is a object

Question Six

a. Write a function called myMap that takes in an array and a callback as arguments. It should return a new array with the callback applied to each element in the array.

Input: [3,5,6], function(num) { return num * 3 }

Output: [9, 15, 18]

b. Create a function allCaps that takes in an array as an argument, and uses the myMap function to return all the elements capitalized.

Input: ["The", "internet", "is", "not", "a", "big", "truck.", "It's", "a", "series", "of", "tubes"]

Output:

[
    'THE', 'INTERNET',
     'IS',      'NOT',
      'A',      'BIG',
 'TRUCK.',     "IT'S",
      'A',   'SERIES',
     'OF',    'TUBES'
]

Question Seven

a. Write a function called myFilter that takes in an array and a callback as arguments. The callback should take in an element and return a boolean. myFilter should return a new array with only values that return true when passed into the callback.

Input: [1,4,6,7, -3], num => num < 5

Output:  [1, 4, -3]

b. Write a function called removeEvenNumbers that takes in an array and returns an array with all the even numbers removed.

Input: [1,2,3,4,5,6,7,8,9]
Output: [1,3,5,7,9]

c. Write a function called removeShortWords that takes in an array and returns an array with all strings containing fewer than 4 characters removed.

Input: ["JavaScript", "is", "a", "high-level,", "interpreted", "programming", "language", "that", "conforms", "to", "the", "ECMAScript", "specification"]

Output:
[ 'JavaScript',
  'high-level,',
  'interpreted',
  'programming',
  'language',
  'that',
  'conforms',
  'ECMAScript',
  'specification' ]