Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial


Maggie Lodge
Maggie Lodge
3,373 Points

Random number function question

What is the difference between these two lines of code? They both return random numbers in the Console log.

  const randomNumber = Math.floor(Math.random() * (upper-lower+1)) + lower;
  const randomNumber = Math.floor(Math.random() * (upper)) + lower;

1 Answer

Steven Parker
Steven Parker
229,967 Points

The first line implements the standard formula for a random number between (inclusively) two values. For example, if "lower" was set at 100 and "upper" was set at 200, the final result would always be at least 100 and never higher than 200.

The second line isn't a standard formula. Given the same example with "lower" and "upper" set at 100 and 200, the value generated would also be at least 100 but could be as high as 299.