After reading the great answer for Absolute Beginner\'s Guide to Bit Shifting? I tested the claim (sic):
3,758,096,384 << 1
from Chrome
It returns 768 because you're incorrectly using the comma operator. 3,758,096,384 << 1 will actually be 384 << 1 because the comma operator will return the last operand.
384 << 1