Why these syntactically identical functions produce different results?

Question

function foo1() {
    return {
        bar: "hello"
    };
}

function foo2() {
    return
    {
        bar: "hello"
    };
}

console.log(foo1());
console.log(foo2());

Can I get an explanation why the two functions print out different results even though the code looks the same?

And also a [helpful link](http://stackoverflow.com/questions/2846283/what-are-the-rules-for-javascripts-automatic-semicolon-insertion-asi) for you. — Rajaprabhu Aravindasamy, Jul 21 '16 at 07:00

thefourtheye · Accepted Answer · 2016-07-21T06:55:46.043

Automatic semicolon insertion

Quoting the specification,

When a continue, break, return, throw, or yield token is encountered and a LineTerminator is encountered before the next token, a semicolon is automatically inserted after the continue, break, return, throw, or yield token.

So the code will become like this

function foo2() {
    return;          // Note the `;` after `return`
    {
        bar: "hello"
    };
}

The return statement terminates and then there is an object after that, which is basically unreachable code. Since the return statement doesn't return anything explicitly, undefined will be returned.

Why these syntactically identical functions produce different results?

1 Answers1