The >>> operator is just like the >> operator, except that the bits shifted in on the left are always zero, regardless of the sign of the first operand. For example, -1 >>4 evaluates to -1, but -1 >>> 4 evaluates to 268435455 (0x0fffffff).From JavaScript: The Definitive Guide.
<<带符号左移 (n<<2 将整型值带符号左移2位 )
>>>无符号右移 (n>>>2 将整型值无符号右移2位 )随便GOOGLE出来的结果