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Printing the pages in reverse order
Loops6/28
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  • 1. New project: driver development
  • 2. Managing the number of copies
  • 3. Learning the for loop
  • 4. Correcting the loop
  • 5. Printing the pages in reverse order
  • 6. Printing only odd pages
  • 7. Printing only even pages
  • 8. Printing driver: copy mode
  • 9. Printing driver: all pages
  • 10. Printing driver: pages in reverse order
  • 11. Print driver: even and odd pages
  • 12. Print driver: switching evens and odds
  • 13. Accumulation in the loop
  • 14. Checks in loops
  • 15. Searching for an even number
  • 16. How much does printing cost?
  • 17. Economy printing
  • 18. Saving ink
  • 19. Summary of “Loops”. Part 1
  • 20. Third program: “Protein shake!”
  • 21. It’s been a “while”
  • 22. The while loop, summation
  • 23. Another project: a dart machine
  • 24. Dart machine: accumulating misses
  • 25. Dart machine: defeat
  • 26. Dart machine: final scoreboard
  • 27. Summary of “Loops”. Part 2
  • 28. Fourth program: “Mad Dryer”
Printing only even pages
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  • Theory
  • Theory
  • Comments

Printing only odd pages

Look at how quickly you are getting along! Let’s remember what else a printer should be able to do:

The new printer is simple enough, it should be able to print all the pages in direct and reverse order, print even and odd pages and make copies of one page.

All we have to do is print even and odd pages. Printing only odd pages is easy:

  • You need to start printing from the first page.
  • After each iteration of the loop, you need to increase the number of the current page by 2, and not by 1.

Perhaps you already noticed that in loops, an increase or decrease of variables by some number is regularly used. And we constantly have to write cumbersome structures, such as page = page + 1. Fortunately, JavaScript has several convenient operators that allow us to shorten the code. Here they are:

NameExampleAnalog
Increment (increase by one)i++i = i + 1
Decrement (decrease by one)i--i = i - 1
C-c-combo!i += 2i = i + 2

You can combine not only addition, but also other mathematical operations: subtraction -=, multiplication *=, division /= and calculating the remainder %=. For example, i *= 10 will do the same as i = i * 10.

Comments

  • script.js
JavaScript
var totalPages = 7; for (var page = 1; page <= totalPages; page++) { muffin.print(page); }

What didn’t you like in this task?

Thanks! We’ll fix everything at once!

Console

The code has changed, click “Run” or turn autorun on.

Result

Goalscompleted

Let’s print only odd pages.

  1. Replace the operation of increasing the page number from page++ to page += 2.
  2. Change the number of pages from 7 to 12.

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