javascript 十进制转 8/16/32 进制的转换

var id = 128;

var id_8B  = alarm_id & 0x000000ff;

var id_16B = (alarm_id & 0x0000ff00) >> 8;

var id_24B = (alarm_id & 0x00ff0000) >> 16;

var id_32B = (alarm_id & 0xff000000) >> 24;