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

Omar Farag
Omar Farag
4,573 Points
Posted by Omar Farag
Omar Farag
4,573 Points

Function not working

When the alert pops up, "undefined" appears instead of a number value.

function randomNum (bttmNum, topNum) {
  Math.floor(Math.random() * (topNum - bttmNum + bttmNum)) + bttmNum; 
}
 alert(randomNum (11, 14));

3 Answers

Rick Buffington
Rick Buffington
8,146 Points
Rick Buffington
Rick Buffington
8,146 Points

3 things: 1) When you are multiplying your random number * (topNum - bttmNum + bttmNum) you are being redundant. You are subtracting bttmNum and then adding it again. This would be the same as adding 0 :). I think the idea is to +1 instead of the bttmNum to make up for the random generators decimal value. 2) You aren't assigning your random number to anything

var myNum = Math.floor(...)

3) You aren't returning anything. Your function really needs to return a value in order to be useful.

Hope that helps.

Omar Farag
Omar Farag
4,573 Points
Omar Farag
Omar Farag
4,573 Points

For some reason this function returns values above 14 sometimes...

function randomNum (bttmNum, topNum) {
  var dieRoll = Math.floor(Math.random() * (topNum + 1)) + bttmNum; 
  return dieRoll;
}
 alert(randomNum (3, 14));
Rick Buffington
Rick Buffington
8,146 Points
Rick Buffington
Rick Buffington
8,146 Points

You've got it - however, if you compare your Math.floor() setup, you'll see that they subtract the bottom number from the top number and then +1.

var dieRoll = Math.floor(Math.random() * (topNum - bttmNum + 1)) + bttmNum;