TypeScript · Middle · Question 75 of 75

What does `switch (true)` narrowing (TS 5.3) enable?

switch (true) {
  case typeof x === 'string': return x.toUpperCase();
  case Array.isArray(x): return x.length;
}

✓Correct answer: Each case condition narrows the value inside that branch
2It disables narrowing
3It requires an enum

Explanation

It's a readable alternative to long if/else if chains with type guards.

Further reading

TS 5.3: switch (true) narrowing ↗

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