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

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
231,275 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.

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