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✏️ Practice: Looping with for

Goal: In the last lesson, we learned:

  • The three parameters of a for loop
  • How to use a for loop both with and without arrays

Practice utilizing for loops in a variety of ways by completing one of the exercises detailed below.

Warm Up​

  • What is the difference between for and Array.prototype.forEach() loops? Why should you generally favor Array.prototype.forEach()?
  • How does a for loop know when to stop looping?
  • What is the last parameter in a for loop and what is it for?

Code​

Complete one of the exercises below.

Count Up By​

Create a program that takes two numbers — one to count to and another to determine what multiple to use to get there.

Here is some sample input:


Count to: 30
Count by: 5
Output: 5, 10, 15, 20, 25, 30

Count to: 50
Count by: 7
Output: 7, 14, 21, 28, 35, 42, 49

Don't forget to consider how to handle any input that might be submitted:

  • Empty values (user just presses enter)
  • Non-numeric values (It may be helpful to read up about the numerical value, NaN)
  • Negative numbers
  • Count by number is larger than the count to numbers

Turn forEach() into For​

Go back through the looping practice problems, and redo one of them with a for loop instead of a forEach() loop.

Word Puzzle​

Create a website that uses a method to replace vowels in a string with the dash symbol "-" to create a word puzzle to solve. Hide the original string when you show the resulting word puzzle, so that another person can try and guess it.

Example:

String Input: "Believe you can and you're halfway there. Theodore Roosevelt"

Puzzle Output: "B-l--v- y-- c-n -nd y--'r- h-lfw-y th-r-. Th--d-r- R--s-v-lt"

Do this without regular expressions. (If you don't know what a regular expression is yet, don't worry — we will be covering them in a future lesson.)

Peer Code Review​

  • Is the business logic and user interface logic distinctly separate?
  • Are variable names descriptive and in lower camelCase?
  • Does the code have proper indentation and spacing throughout?
  • Are for loops being used correctly?
  • Are forEach()loops being used correctly?