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Question 1 of 40

What will be the output of this code?

interface A {
  type: 'a';
  aProp: string;
}
interface B {
  type: 'b';
  bProp: number;
}

function printVal(x: A | B) {
  if (x.type === 'a') {
    console.log(x.aProp);
  } else {
    console.log(x.bProp);
  }
}

printVal({ type: 'a', aProp: 'foo' });

(Choose one correct answer)

undefined

Error at runtime

foo

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