Why does 3,758,096,384 << 1 give 768

Question

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 console:

3,758,096,384 << 1

> 768

3,758,096,384 << 2

> 1536

3758096384 << 1

> -1073741824

Answer 1

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.

Answer 2

That's the comma operator at work. It's actually 384 << 1. (The comma operator evaluates its left hand side, then evaluates its right hand side, and returns the right hand side.)