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JavaScript

Posted by Molly Robinson
Molly Robinson
770 Points

Does the program KNOW which number is the max and which is the min, or do I have to tell it?

To put it another way, when he writes

var randomNumber = Math.floor(Math.random() * (topNumber - bottomNumber + 1 )) + bottomNumber;

is there a step where we are supposed to ensure that "topNumber" is a larger number than "bottomNumber," or is that arbitrary? will it work out even if "topNumber" is smaller?

This really got me when I was trying to do the second challenge on my own. I felt I HAD to make sure the program KNEW which number was the largest and which was the smallest.

But, aside from the way he (the teacher) labels the keywords for the numbers, I'm honestly unsure if they represent a real (maybe necessary) value difference or not. (topNumber having to always be the larger number and bottomNumber having to always be the smaller number).

Matthew Long
Matthew Long
28,407 Points

topNumber and bottomNumber must be defined. As you have them they are referencing variables that you have not defined and therefore randomNumber is undefined. Without setting topNumber and bottomNumber such as var topNumber = 4; and var bottomNumber = 1;, for example, then you will receive an error.

1 Answer

Jennifer Nordell
seal-mask
STAFF
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Hi there! You haven't included the link to the video here, but if I'm not mistaken elsewhere in the program the max and the min are either set or sent in as arguments to a function where this line is found.

In some scenarios, you will know in advance what the minimum number is and the maximum number. Let's say for example a 6 sided die. You know the minimum will always be 1 and the maximum will always be 6.

But what if you don't know? What if you want the user to choose the minimum and maximum? There are a couple of ways to handle this. Either you could keep prompting the user for the minimum and maximum and directing them to put a minimum number that is lower than the maximum or you could do something a little different. You could get the absolute value of the difference. For example, if they put in a minimum of 1 and a maximum of 6, then it would work as expected and the max minus the min would be equal to 5.

Users are wildly unpredictable. So if you got the absolute value and they put in a minimum of 6 and a maximum of 1, then the difference between max minus min would be -5. But the absolute value of either 5 or -5 is still 5. You could potentially just ask the user to put in two arbitrary numbers and get the absolute value of it and take out the guess work and error messages all together.

You can find documentation on the abs method here.

Hope this helps! :sparkles: