function bitRev7(n) {

	// 8-bit rev bithack
	n = ((n & 0b10101010) >> 1) | ((n & 0b01010101) << 1);
	n = ((n & 0b11001100) >> 2) | ((n & 0b00110011) << 2);
	n = ((n & 0b11110000) >> 4) | ((n & 0b00001111) << 4);

	return n >> 1; // shift off 0th bit (giving us a 7-bit rev overall)
}
let ans = 0;
for (let i = 0; i < (1 << 7); i++) {
	ans = ans ^ bitRev7(i);
}

function bitRev7(n) {
	return parseInt(n.toString(2).split("").reverse().join("").padEnd(7, "0"), 2);
}
let ans = 0;
for (let i = 0; i < (1 << 7); i++) {
	ans = ans ^ bitRev7(i);
}