Labels that are declared and not used anywhere in the code are most likely an error due to incomplete refactoring.

OUTER_LOOP:
for (const student of students) {
    if (checkScores(student.scores)) {
        continue;
    }
    doSomething(student);
}

In this case, probably removing OUTER_LOOP: had been forgotten. Such labels take up space in the code and can lead to confusion by readers.

A: var foo = 0;

B: {
    foo();
}

C:
for (let i = 0; i < 10; ++i) {
    foo();
}

A: {
    if (foo()) {
        break A;
    }
    bar();
}

B:
for (let i = 0; i < 10; ++i) {
    if (foo()) {
        break B;
    }
    bar();
}

blurt / blurt