What is the best way to verify and handle an undefined array in order to display an error message?

Question

What is the best way to verify and handle an undefined array in order to display an error message?

Currently working on a ternary statement to display the certification of a movie (e.g. PG, R...).

If the array length is zero or undefined, I'm aiming to output an error message stating "No Certification Available For This Movie". While I have successfully managed to display the error message when the array is empty, I'm facing a challenge in handling undefined arrays. I constantly receive a console error reading

TypeError: Cannot read properties of undefined (reading 'release_dates')

.

Below is my attempt so far:

 const movieRating = rating.results;

 //Fetching US ratings
 const findUSRating = movieRating.find((item) => item.iso_3166_1 === 'US');

//Applying filter to remove null certifications from US ratings.
 const array = findUSRating.release_dates.filter((item) => item.certification);

//Ternary statement & my current hurdle.
console.log(array.length > 0 || array[index] !== undefined ? array[0].certification : `No Certification Available For This Movie`);

javascript arrays conditional-operator

Answer 1

Answer №1

Issue: Cannot access properties of undefined (reading 'release_dates')

It seems that the variable findUSRating is not defined. This error occurs because the object within movieRating does not have the property with iso_3166_1 set to US.

For instance, consider the following:

const movieRating = [{
    iso_3166_1: 'Canada'
}, {
    iso_3166_1: 'Australia'
}];

 //Finding US ratings
 const findUSRating = movieRating.find((item) => item.iso_3166_1 === 'US');

//Filtering US ratings to remove null certifications. 
 const array = findUSRating.release_dates.filter((item) => item.certification);
 
 console.log(array);

To resolve this issue, you can utilize the Optional chaining (?.) operator.

Check out the Live Demo below:

const movieRating = [{
    iso_3166_1: 'US',
  release_dates: [{
    certification: 'A'
  }]
}, {
    iso_3166_1: 'Australia',
  release_dates: [{
    certification: 'B'
  }]
}];

 //Finding US ratings
 const findUSRating = movieRating?.find((item) => item.iso_3166_1 === 'US');

//Filtering US ratings to remove null certifications. 
 const array = findUSRating?.release_dates.filter((item) => item.certification);
 
console.log(array?.length > 0 || array !== undefined ? array[0].certification : `No certification Available For This Movie`);

Answer 2

Issue: Cannot access properties of undefined (reading 'release_dates')

It seems that the variable findUSRating is not defined. This error occurs because the object within movieRating does not have the property with iso_3166_1 set to US.

For instance, consider the following:

const movieRating = [{
    iso_3166_1: 'Canada'
}, {
    iso_3166_1: 'Australia'
}];

 //Finding US ratings
 const findUSRating = movieRating.find((item) => item.iso_3166_1 === 'US');

//Filtering US ratings to remove null certifications. 
 const array = findUSRating.release_dates.filter((item) => item.certification);
 
 console.log(array);

To resolve this issue, you can utilize the Optional chaining (?.) operator.

Check out the Live Demo below:

const movieRating = [{
    iso_3166_1: 'US',
  release_dates: [{
    certification: 'A'
  }]
}, {
    iso_3166_1: 'Australia',
  release_dates: [{
    certification: 'B'
  }]
}];

 //Finding US ratings
 const findUSRating = movieRating?.find((item) => item.iso_3166_1 === 'US');

//Filtering US ratings to remove null certifications. 
 const array = findUSRating?.release_dates.filter((item) => item.certification);
 
console.log(array?.length > 0 || array !== undefined ? array[0].certification : `No certification Available For This Movie`);

Answer 3

Answer №2

The problem lies within this specific line of code

 const array = findUSRating.release_dates.filter((item) => item.certification);

Attempting to access findUSRating.release_dates when findUSRating is undefined.

A potential solution is to add a conditional check before accessing the property

const array = (findUSRating && findUSRating.release_dates) ? findUSRating.release_dates.filter((item) => item.certification) : [];

You may encounter a similar issue if movieRating is undefined or not an array. It's advisable to implement a similar approach to avoid errors

 const findUSRating = (movieRating && movieRating.length) ? movieRating.find((item) => item.iso_3166_1 === 'US') : [];

Answer 4

The problem lies within this specific line of code

 const array = findUSRating.release_dates.filter((item) => item.certification);

Attempting to access findUSRating.release_dates when findUSRating is undefined.

A potential solution is to add a conditional check before accessing the property

const array = (findUSRating && findUSRating.release_dates) ? findUSRating.release_dates.filter((item) => item.certification) : [];

You may encounter a similar issue if movieRating is undefined or not an array. It's advisable to implement a similar approach to avoid errors

 const findUSRating = (movieRating && movieRating.length) ? movieRating.find((item) => item.iso_3166_1 === 'US') : [];

Answer 5

Answer №3

By utilizing try catch, you can effectively handle any runtime errors that may occur.

try {
  const movieRating = rating.results;

   //Locating US ratings
   const findUSRating = movieRating.find((item) => item.iso_3166_1 === 'US');

  //Filtering US ratings to eliminate null certifications.
   const array = findUSRating.release_dates.filter((item) => item.certification);

  //Ternary statement & where I am struggling.
  console.log(array.length > 0 || array[index] !== undefined ?    array[0].certification : `No certification Available For This Movie`);
} catch(err) 
{ 
  console.log("Error") 
}

Answer 6

By utilizing try catch, you can effectively handle any runtime errors that may occur.

try {
  const movieRating = rating.results;

   //Locating US ratings
   const findUSRating = movieRating.find((item) => item.iso_3166_1 === 'US');

  //Filtering US ratings to eliminate null certifications.
   const array = findUSRating.release_dates.filter((item) => item.certification);

  //Ternary statement & where I am struggling.
  console.log(array.length > 0 || array[index] !== undefined ?    array[0].certification : `No certification Available For This Movie`);
} catch(err) 
{ 
  console.log("Error") 
}

Answer 7

Answer №4

@Quinn. Feel free to modify the code snippet below.

//Removing null certifications from US ratings. 
const array = findUSRating.release_dates.filter((item) => item.certification);

const array = findUSRating ? findUSRating.release_dates.filter((item) => item.certification) : [];

     or

const array = findUSRating?.release_dates?.filter((item) => item.certification);

Hope this adjustment is useful.

Answer 8

@Quinn. Feel free to modify the code snippet below.

//Removing null certifications from US ratings. 
const array = findUSRating.release_dates.filter((item) => item.certification);

const array = findUSRating ? findUSRating.release_dates.filter((item) => item.certification) : [];

     or

const array = findUSRating?.release_dates?.filter((item) => item.certification);

Hope this adjustment is useful.

What is the best way to verify and handle an undefined array in order to display an error message?

Answer №1

Answer №2

Answer №3

Answer №4

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