The process of extracting a value from an array of objects encountered an error due to the undefined object

Question

The process of extracting a value from an array of objects encountered an error due to the undefined object

I am looking to extract the value from an array within an object while also implementing error checking. The code I currently have checks if a specific key exists in the object and if the value associated with that key is of type array. If both conditions are met, I want to retrieve the value from that key. While my current approach seems functional, I am wondering if there is a more efficient way to achieve this. I attempted using const [value] = obj?.the_key, but received an exception

Uncaught TypeError: undefined is not iterable (cannot read property Symbol(Symbol.iterator))

when the value associated with 'theKey' is not an array or if 'theKey' does not exist within the object.

const obj = {'theKey': ['correct value']}
const hasKey = obj['theKey'] !== undefined && Array.isArray(obj.theKey)
if (!hasKey) console.log('null')
const [value] = obj.theKey
console.log(value)

javascript typescript

Answer 1

Answer №1

To verify if your object contains the specific key or property you are searching for, utilize the hasOwnProperty and isArray methods.

const obj = { 'theKey' : ['correct value'] };

let hasKey = obj.hasOwnProperty('theKey'); // This will result in either true or false

if (!hasKey) { // indicates that the key does not exist

   // implement error handling logic

}

Subsequently, assess the data type of the value to determine whether it is an array or not.

if (hasKey) {

   let keyVal = obj.theKey;

   if (Array.isArray(keyVal)) { // results in true or false

      // execute business logic with array

   } else { // the key value is not an array

      // perform error handling

   }
}

Answer 2

To verify if your object contains the specific key or property you are searching for, utilize the hasOwnProperty and isArray methods.

const obj = { 'theKey' : ['correct value'] };

let hasKey = obj.hasOwnProperty('theKey'); // This will result in either true or false

if (!hasKey) { // indicates that the key does not exist

   // implement error handling logic

}

Subsequently, assess the data type of the value to determine whether it is an array or not.

if (hasKey) {

   let keyVal = obj.theKey;

   if (Array.isArray(keyVal)) { // results in true or false

      // execute business logic with array

   } else { // the key value is not an array

      // perform error handling

   }
}

The process of extracting a value from an array of objects encountered an error due to the undefined object

Answer №1

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