Rename Number.prototype.clz to Math.clz

Jason Orendorff jason.orendorff at gmail.com
Thu Jan 16 08:40:03 PST 2014


At the risk of putting too many nails in the board...

The rationale seems to propose that (0).clz() === 32, but the
hypothetical uint64(0).clz() would return 64. That seems like a bad
idea though. It's weird for two zero values to get such different
behavior from the same method. It's weird for floating-point numbers
to have a clz() method in the first place.

Since these are two different mathematical functions, they should have
different names: Math.clz32(zero) would be 32 no matter what type of
zero you pass it; the hypothetical Math.clz64(zero) would of course be
64. That way users can focus on the mathematical function being
computed, rather than runtime types.

Or maybe: flip the function around so that it returns the number of
bits in the binary expansion of the value: Math.bitlen(15) === 4. This
is just (32 - CLZ), so it effectively computes the same thing as clz.
The advantage is that it extends naturally to integers of any size.

-j


More information about the es-discuss mailing list