JavaScript Object method not changing property

Question

I am building a factory function to manage Ship objects for a battleship game. So far I have the following:

    const Ship = (name, length, orientation = 'horizontal') => {
  let sunk = false;
  const hits = Array(length).fill(false);

  const hit = (position) => {
    if (position <= hits.length) hits[position] = true;
  };

  function sink() {
    sunk = true;
  }

  return {
    name,
    length,
    orientation,
    sunk,
    hits,
    hit,
    sink,
  };
};

I am testing the sink() method to change the sunk property boolean from false to true. However, whenever I run:

example.sink() example.sunk sunk always remains false.

Where am I going wrong?

For some reason the hit() method alters the hits propertyfine. Butsink()is not altering thesunk` property.

Thanks

sunk is a boolean value, not an array ref like hits. The object returned by Ship isn't re-evaluated, so the value will always be the same. — Dave Newton
– Dave Newton, Commented Aug 25, 2021 at 8:13
@LearningPython I'd probably take a quick step back and find some good JS OOP tutorials, then decide which JS OOP approach you want to take. There are several ways this could be approached. — Dave Newton
– Dave Newton, Commented Aug 25, 2021 at 8:17

KooiInc · Accepted Answer · 2021-08-25 08:25:21Z

1

You can use getters to retrieve the values:

const Ship = (name, length, orientation = 'horizontal') => {
  let sunk = false;
  const hits = Array(length).fill(false);

  const hit = position => {
    if (position <= hits.length) hits[position] = true;
  };

  function sink() {
    sunk = true;
  }

  return {
    name,
    length,
    orientation,
    hit,
    sink,
    // get values using getters
    get sunk() { return sunk; },
    get hits() { return hits; },
  };
};

const someShip = Ship(`ss something`, 100, `vertical`);
someShip.sink();
console.log(someShip.sunk);

answered Aug 25, 2021 at 8:25

KooiInc

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DecPK · Accepted Answer · 2021-08-25 08:18:12Z

0

You can create a API method to access the local sunk method

const Ship = (name, length, orientation = "horizontal") => {
  let sunk = false;
  const hits = Array(length).fill(false);

  const hit = (position) => {
    if (position <= hits.length) hits[position] = true;
  };

  function sink() {
    sunk = true;
  }

  function getSunk() {
    return sunk;
  }

  return {
    name,
    length,
    orientation,
    hits,
    hit,
    sink,
    getSunk,
  };
};

const ship = Ship("a", 10);
console.log(ship.getSunk());
ship.sink();
console.log(ship.getSunk());

answered Aug 25, 2021 at 8:18

DecPK

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