(Bitwise Left Shift And Assignment) - MACROMEDIA FLASH MX 2004-ACTIONSCRIPT LANGUAGE Reference

<<= (bitwise left shift and assignment)
Availability
Flash Player 5.
Usage
expression1 <<= expression2
Parameters
expression1
expression2
Returns
A 32-bit integer.
Description
Operator (bitwise compound assignment); this operator performs a bitwise left shift (<<=)
operation and stores the contents as a result in
equivalent:
A <<= B
A = (A << B)
For more information, see "Operator precedence and associativity" in Using ActionScript in Flash.
Example
In the following example, you use the bitwise left shift and assignment (<<=) operator to shift all
bits one space to the left:
var x:Number = 4;
// shift all bits one slot to the left.
x <<= 1;
trace(x); // output: 8
// 4 decimal = 0100 binary
// 8 decimal = 1000 binary
See also
<< (bitwise left shift),
76 Chapter 2: ActionScript Language Reference
A number or expression to be shifted left.
A number or expression that converts to an integer from 0 to 31.
>>= (bitwise right shift and
. The following two expressions are
expression1
assignment), >> (bitwise right shift)