4 Ways to Safely Access Nested Objects in Vanilla Javascript

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Thu Mar 18 2021 15:05:49 GMT+0000 (Coordinated Universal Time)

// Example object
const macAyres = {
  tours: {
    nearMe: {
      sanFrancisco: {
        date: 'Sun Oct 27',
        location: 'The Regency Ballroom',
        cost: '30.00',
      },
    },
  }
}



// 1. Ternary Operator to Check for null/undefined
const concertLocation = (macAyres.tours && 
  						 macAyres.tours.nearMe &&
						 macAyres.tours.nearMe.sanJose) 
	? macAyres.tours.nearMe.sanJose.location 
	: undefined;



// 2. Oliver Steele’s Nested Object Access Pattern
const concertLocation = (macAyres.tours.nearMe.sanJose || {}).location;

/* Explanation: 
As the || operator breaks return the truthy value encountered, the above expression would return macAyres.tours.nearMe.sanJose if it is not null/undefined, otherwise {}.
In this case, we will be accessing location from an empty object, and not from undefined, so we will avoid getting the error.
*/



// 3. Array Reduce
const paths = ['tours', 'nearMe', 'sanJose', 'location'];
const location = paths.reduce((object, path) => {
    return (object || {})[path]; // Oliver Steele's pattern
}, macAyres)




// 4. 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');

COPY

Really usefull, specially when working with Vue / React / Angular in large API's, or with dynamic data.

https://betterprogramming.pub/4-ways-to-safely-access-nested-objects-in-vanilla-javascript-8671d09348a8

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4 Ways to Safely Access Nested Objects in Vanilla Javascript

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