How to check if an element exists within an object of arrays

Question

I'm trying to check if an array within an object contains an element userAnswer or not. Is there a good way to do this using es6. I've tried a few however, I can't seem to get it to work properly. Most of my attempts return an error. Any help would be appreciated.

Last Attempt

conductedExam.questions.some(question => question.userAnswer.includes(Object))

Data

{
  _id: '1',
  questions: [
    { name: '1', userAnswer: 'one' },
    { name: '2', userAnswer: 'two' },
    { name: '2' }
  ]
};

What is the Object that you're passing to the .includes? Is that an actual object, or a string like 'one', or what? Not entirely sure what the logic you're looking for is — CertainPerformance
– CertainPerformance, Commented May 11, 2019 at 0:36
Sorry, this might be my noob problem. I thought Object meant to check if any object exists. Is that possible or am I not looking at this correctly. — bp123
– bp123, Commented May 11, 2019 at 0:38
Because no object exists at any of the userAnswers in the given input, would you want the output to be false here? (you only have strings) — CertainPerformance
– CertainPerformance, Commented May 11, 2019 at 0:39

Jack Bashford · Accepted Answer · 2019-05-11 00:53:31Z

1

Use hasOwnProperty:

const conductedExam = {
  _id: '1',
  questions: [
    { name: '1', userAnswer: 'one' },
    { name: '2', userAnswer: 'two' },
    { name: '2' }
  ]
};

console.log(conductedExam.questions.some(e => !e.hasOwnProperty("userAnswer")));

edited May 11, 2019 at 0:53

answered May 11, 2019 at 0:37

Jack Bashford

44.3k11 gold badges56 silver badges84 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

bp123 Over a year ago

I want it to return true if it doesn't exist and false if it does exists

Jack Bashford Over a year ago

Oh, right - fixed @bp123. Does that work for you now?

Jack Bashford Over a year ago

@bp123 It still returns true because one element in the array doesn't have the property. Do you want to return false if all elements have the property and true if no elements have the property?

Ryan Abis · Accepted Answer · 2019-05-11 00:40:00Z

0

Using hasOwnProperty might work.

conductedExam.questions.some(question => question.hasOwnProperty('userAnswer')) returns true

answered May 11, 2019 at 0:40

Ryan Abis

262 bronze badges

Collectives™ on Stack Overflow

How to check if an element exists within an object of arrays

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related