[dukky]

I really don't see why this isn't a syntax error

What is actually being done with the calls after the chain of +'s?

Edit: Something to do with semicolons being optional in js?

[d4n3]

Javascript has "semicolon insertion".

It tries to parse a newline with no semicolon as continuing the current expression, if it can't, it inserts a semicolon.

It's a 'feature' that's caused too many bugs and is a warning in most linters.

[afandian]

This is valid JS:

    1;
    2;
    alert("returns undefined");
    confirm("return true or false?")
    (function() {return 3})();
    (function() {})();

What's being done with the values of 1, 2, undefined, true/false, 3 and undefined? Nothing if they're not assigned. But as every function returns a value and invocations are therefore an expression, it would be impossible to disallow expressions to be evaluated but not assigned.