I ran the following code in turn in Chrome Javascript Console

{f}={f:3} // it created a new variable f with a value of 3

{f}={f:3}; // Uncaught SyntaxError: Unexpected token '='

{f}={f:3} // There is a blank line on it，error: Uncaught SyntaxError: Unexpected token '='

Why do they behave differently?

What I really want to ask is why the bad code run without error in the first case.

The problem extends from here: object_destructuring - Assignment separate from declaration