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JavaScript JavaScript Basics (Retired) Working With Numbers The Random Challenge Solution

Andrew Zhao
Andrew Zhao
3,267 Points
Posted by Andrew Zhao
Andrew Zhao
3,267 Points

Can't we just use parseInt() to round instead of using Math.floor() ?

var input = prompt("Please type a number");
var topNumber = parseInt(input);
var randomNumber = Math.floor(Math.random() * topNumber) + 1;
var message = "<p>" + random number + " is a number between 1 and " + topNumber + ".</p>";
document.write(message);

In the above Code, is it not possible to subsitute line 3 with: var randomNumber = parseInt(Math.random() * topNumber) + 1 ?

1 Answer

Nicholas Hebb
Nicholas Hebb
18,872 Points

I tried a bunch of edge cases to see whether I could get parseInt() to fail. I couldn't, so I suppose you could write it that way. However, the other issue is maintainability - especially if someone else needs to read your code and understand your intent. Since parseInt() is designed to parse strings into integers, and Math.floor() is designed to truncate a float to its integer part, I think that using Math.floor() makes your intent clearer.

Andrew Zhao
Andrew Zhao
3,267 Points
Andrew Zhao
Andrew Zhao
3,267 Points

Thank you very, very much Nick.

By the way, what is an edge case?

Nicholas Hebb
Nicholas Hebb
18,872 Points

Edge case typically means testing a minimum or maximum input value. In this scenario, I tested values 0 and 0.5 to see whether the outcomes might vary between Math.floor() and parseInt().