Block Scope

To enforce block-scoping in JavaScript, the let keyword can be used. It makes variables inaccessible from the outside of their blocks:

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function myFunction(): void {
  if (true) {
    let myNumber = 1337;
  }
  // Will throw a `ReferenceError` because `myNumber` is not defined
  return myNumber;
}

console.log(myFunction()); // Causes an uncaught `ReferenceError`