lodash：数组过滤器，按对象排除

Question

I have an Array a of Questions :

[
  {id: 1,name: "Question 1"},
  {id: 2,name: "Question 2"},
  {id: 3,name: "Question 3"},
]

and an Array b of Answers , where the property question_id references the property id of Array a :

[
  {id: 1, question_id: 2,name: "My Answer to Question 2"}
]

With lodash, I want to filter Array a to exlude all the Answers that are referencing to it, expecting the output:

[
  {id: 1,name: "Question 1"},
  {id: 3,name: "Question 3"},
]

Answer 1

var questions = [
    {id: 1,name: "Question 1"},
    {id: 2,name: "Question 2"},
    {id: 3,name: "Question 3"},
];

var answers = [
    {id: 1, question_id: 2,name: "My Answer to Question 2"}
];

var filtered = _.filter(questions, isNotReferencedByAnyAnswer);

function isNotReferencedByAnyAnswer(question) {
    return _.findIndex(answers, {'question_id': question.id}) === -1;
}

Answer 2

A short answer with lodash.differenceWith

arr = [
       {id: 1,name: "Question 1"},
       {id: 2,name: "Question 2"},
       {id: 3,name: "Question 3"},
]
arr1 = [
  {id: 1, question_id: 2,name: "My Answer to Question 2"}
]
_.differenceWith(arr, arr1, (arrVal, othVal) => arrVal.id === othVal.question_id)

// result

[ { id: 1, name: 'Question 1' }, { id: 3, name: 'Question 3' } ]