Using Node.js, I'm evaluating the expression:
0 < Number.MIN_VALUE
To my surprise, this returns true. Why is that? And: How can I get the smallest number available for which the comparison works as expected?
5 Answers
Number.MIN_VALUE is 5e-324, i.e. the smallest positive number that can be represented within float precision, i.e. that's as close as you can get to zero. It defines the best resolution floats give you.
Now the overall smallest value is Number.NEGATIVE_INFINITY although that's not really numeric in the strict sense.
3 Comments
Golo Roden
Thanks for explaining the behavior and pointing out a viable alternative :-)
Felipe
I can't believe I actually had to look this up to find out why my code was wrong. I swear, javascript, sometimes...
chharvey
I would say
Number.NEGATIVE_INFINITY is the least value (in the sense that no other values can be lesser), but not the smallest. The word "small" implies a small quantity, i.e. a value closer to 0, and "large" implies a value farther away from zero (-1000 is "larger" than 10). So in that sense, -Infinity is quite large, even if it is negative.Number.MIN_VALUE is equivalent to 5e-324 , which is greater than 0.
1 Comment
chharvey
This is true. I think what's throwing people off is the negative exponent
-324. I taught high schoolers who thought that 3 ** -2 === -9.Since Number.MIN_VALUE = 5e-324 = 5 x 10^-324 and it's greater than 0(a little bit greater).
Read more here.
2 Comments
Golo Roden
Number.MIN_SAFE_INTEGER is undefined in Node.js 0.10.x.chharvey
Yes, sometimes people forget
e notation. A positive number raised to a negative exponent is still positive. I taught high schoolers who thought that 3 ** -2 === -9.`Number.MIN_VALUE` is equal to 5e-324 or 5*(10^-324);
it's math. any positive number is greater than zero.
Comments
Use -Number.MAX_VALUE instead of Number.MIN_VALUE to compare:
0 > -Number.MAX_VALUE returns true.
1 Comment
chharvey
-Number.MAX_VALUE is not equal to Number.MIN_VALUE. Furthermore, -Number.MAX_VALUE is a negative number, so you're saying 0 > [a negative number], which is always true.
Number.MIN_SAFE_INTEGERNumber.MIN_SAFE_INTEGERisundefinedin Node.js 0.10.x.