What is the use case for “break Identifier” in JavaScript?

Question

the spec goes

BreakStatement :   
    break ;
    break [no LineTerminator here] Identifier ;

then it goes

Answer 1

If you look on MDN, there's examples

outer_block: {
    inner_block: {
        console.log('1');
        break outer_block; // breaks out of both inner_block and outer_block
        console.log(':-('); // skipped
    }
    console.log('2'); // skipped
}

as you can see, you can break with an identifier that selects a label higher up in the chain than just the first immediate parent statement.

The default action without an identifier would be

outer_block: {
    inner_block: {
        console.log('1');
        break; // breaks out of the inner_block only
        console.log(':-('); // skipped
    }
    console.log('2'); // still executed, does not break
}

The break has to be inside the label, you can't break labels based on indentifiers that the break is outside of.