When:
- undefined(default) provide suggestions as warnings to editors
- trueunused labels are ignored
- falseraises compiler errors about unused labels
Labels are very rare in JavaScript and typically indicate an attempt to write an object literal:
ts
// @errors: 7028
// @allowUnusedLabels: false
function verifyAge(age: number) {
  // Forgot 'return' statement
  if (age > 18) {
    verified: true;
  }
}// @errors: 7028
// @allowUnusedLabels: false
function verifyAge(age: number) {
  // Forgot 'return' statement
  if (age > 18) {
    verified: true;
  }
}