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JavaScript JavaScript Basics (Retired) Creating Reusable Code with Functions Random Number Challenge

Gustavo Reyes
Gustavo Reyes
2,458 Points
Posted by Gustavo Reyes
Gustavo Reyes
2,458 Points

function getRandomNumber(lower, upper){return Math.floor(Math.random() * (upper - lower + 1)) + lower;}

Can someone explain this function to me in details and all its parameters? Im having a hard time grasping the concept of the conditon in the function . IM not sure how it works

2 Answers

Steven Parker
Steven Parker
229,771 Points
Steven Parker
Steven Parker
229,771 Points

:point_right: Let's break up the statement into steps:

  • upper - lower + 1 :point_left: first, compute how wide the range should be
  • Math.random() * (upper - lower + 1) :point_left: then multiply by random to get a value in that range
  • Math.floor( Math.random() * (upper - lower + 1)) :point_left: then drop any fractional part to get an integer
  • Math.floor(Math.random() * (upper - lower + 1)) + lower :point_left: finally, offset it by the minimum value

So, after all that you have a random number that is an integer and between (inclusive) lower and upper.

Jason Anello
PLUS
Jason Anello
Courses Plus Student 94,610 Points
Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

Hi Gustavo,

I gave an answer to a similar question which might help you out.

https://teamtreehouse.com/community/mathfloor-mathrandom-max-min-1-min-explanation