Solution to eloquentjavascript exercise second 2nd edition (Chapter 8) eloquent javascript

eloquentjavascript_solutions_chapter_8.js

// Solution to eloquentjavascript exercise second 2nd edition
// Chapter 8
// http://eloquentjavascript.net/2nd_edition/preview/08_error.html
// Retry
function MultiplicatorUnitFailure() {}

function primitiveMultiply(a, b) {
  if (Math.random() < 0.5)
    return a * b;
  else
    throw new MultiplicatorUnitFailure();
}

function reliableMultiply1(a, b) {
  try {
    return primitiveMultiply(a, b);
  } catch (e) {
    if (e instanceof MultiplicatorUnitFailure) {
      return reliableMultiply(a, b);
    } else {
      throw e;
    }
  }
}

function reliableMultiply2(a, b) {
  for (;;) {
    try {
      return primitiveMultiply(a, b);
    } catch (e) {
      if (e instanceof MultiplicatorUnitFailure) {
        continue;
      } else
        throw e;
    }
  }
}

console.log(reliableMultiply1(8, 8));
console.log(reliableMultiply1(6, 6));
// ---------------------------------------
// The locked box
function withBoxUnlocked(body) {
  box.unlock();
  try {
    body();
  }
  catch (e) {
    // do nothing
  } finally {
    box.lock();
  } 
}

// Bonus
function withBoxUnlocked(body) {
  var state = box.locked;
  box.unlock();
  try {
    body();
  } catch (e) {
    // do nothing
  } finally {
    if (state) {
      box.lock();
    }
  } 
}

withBoxUnlocked(function() {
  box.content.push("gold piece");
});

withBoxUnlocked(function() {
  throw new Error("Pirates on the horizon! Abort!");
});
console.log(box.locked);
// → true