How to avoid 'cannot read property of undefined' errors?

Question

In my code, I deal with an array that has some entries with many objects nested inside one another, where as some do not. It looks something like the following:

Answer 1

Update:

• If you use JavaScript according to ECMAScript 2020 or later, see optional chaining.
• TypeScript has added support for optional chaining in version 3.7.

// use it like this
obj?.a?.lot?.of?.properties

---

Solution for JavaScript before ECMASCript 2020 or TypeScript older than version 3.7:

A quick workaround is using a try/catch helper function with ES6 arrow function:

function getSafe(fn, defaultVal) {
    try {
        return fn();
    } catch (e) {
        return defaultVal;
    }
}

// use it like this
getSafe(() => obj.a.lot.of.properties);

// or add an optional default value
getSafe(() => obj.a.lot.of.properties, 'nothing');

Working snippet:

function getSafe(fn, defaultVal) {
  try {
    return fn();
  } catch (e) {
    return defaultVal;
  }
}

// use it like this
console.log(getSafe(() => obj.a.lot.of.properties));

// or add an optional default value
console.log(getSafe(() => obj.a.lot.of.properties, 'nothing'));

See this article for details.