Right shifts the value of a variable by the number of bits specified in the value of an expression, maintaining the sign, and assigns the result to the variable.
Using the >>= operator is exactly the same as specifying:
The >>= operator shifts the bits of result right by the number of bits specified in expression. The sign bit of result is used to fill the digits from the left. Digits shifted off the right are discarded. For example, after the following code is evaluated, temp has a value of -4: 14 (11110010 in binary) shifted right two bits equals -4 (11111100 in binary).
Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards, Internet Explorer 11 standards. Also supported in Store apps (Windows 8 and Windows Phone 8.1). See Version Information.