Page 76 - JavaScript

a = 0b1001 >>> 2; // a === 0b0010
a = 0b1001 >>> 3; // a === 0b0001

A negative 32bit value always has the left most bit on:

a = 0b11111111111111111111111111110111 | 0;
console.log(a); // -9
b = a >> 2; // leftmost bit is shifted 1 to the right then new left most bit is set to on
(1)
console.log(b); // -3
b = a >>> 2; // leftmost bit is shifted 1 to the right. the new left most bit is set to off
(0)
console.log(b); // 2147483643

The result of a >>> operation is always positive.
The result of a >> is always the same sign as the shifted value.

Right shift on positive numbers is the equivalent of dividing by the Math.pow(2,n) and flooring the
result:

a = 256.67;
n = 4;
result = (a >> n) === Math.floor( Math.floor(a) / Math.pow(2,n) );
// result is true
a = a >> n; // 16

result = (a >>> n) === Math.floor( Math.floor(a) / Math.pow(2,n) );
// result is true
a = a >>> n; // 16

Right shift zero fill (>>>) on negative numbers is different. As JavaScript does not convert to
unsigned ints when doing bit operations there is no operational equivalent:

a = -256.67;
result = (a >>> n) === Math.floor( Math.floor(a) / Math.pow(2,n) );
// result is false

Bitwise assignment operators

With the exception of not (~) all the above bitwise operators can be used as assignment operators:

a |= b; // same as: a = a | b;
a ^= b; // same as: a = a ^ b;
a &= b; // same as: a = a & b;
a >>= b; // same as: a = a >> b;
a >>>= b; // same as: a = a >>> b;
a <<= b; // same as: a = a << b;

Warning: Javascript uses Big Endian to store integers. This will not always match the Endian of
the device/OS. When using typed arrays with bit lengths greater than 8 bits you should check if the
environment is Little Endian or Big Endian before applying bitwise operations.

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