sstephenson/prototype — comment on commit 460be4691af9e4e92908c9ac707597bad69be57c
File: src/prototype/lang/array.js line 517
By keithamus:

You wouldn't use it over >> (Sign-propagating right shift) because, as the name suggests, it propagates the sign, so `-1 >> 0` is still `-1`. The Zero Fill shift un-signs the int, so `-1 >>> 0` is `0`.

The concern of using these operators to coerce numbers into something you want, is that problems can happen by overflowing (so passing it a larger value than 4294967295), for example `4294967296 >>> 0` returns 0. This may have some very undesired effects depending on the application. So be wary!