Getting first item in an array with a specific parameter empty

Question

Considering this array :

const body = [
  {id: 1,courses: [{title:"course1.1", results:[]}, {title:"course1.2", results:[]}]},
  {id: 2,courses: [{title:"course1.1", results:[]}, {title:"course1.2",results:[]}]},   
];

I'm trying to get the first item in body that have a course with no results.

I tried this :

body.filter(session=>session.courses.filter(course=>course.results.length<=0));

But for a reason that I don't understand it return all items.

Any helps would be really appreciated, thank you!

P.S. I already made some try with Array.some and with a simple forEach, with no luck.

Edit: I forgot to include my jsfiddle test, https://jsfiddle.net/jonathanlaf/4os0fzv1/

Edit2: I know that filter will return all results that match, and that's fine, I can just take the first index of the newly returned array.

Edit3: I actually expect the newly returned array to look like this :

const body2 = [
  {id: 2,courses: [{title:"course1.1", results:[]}, {title:"course1.2",results:[]}]},   
];

try using $.grep(body,function(obj,index1){ if ($.grep(obj.courses,function(course,index2){ if ( course.results.length<=0) {return course; } }).length>0) return obj; }) Please make sure of syntax errors in my code if possible but grep can useful for you. — Dhiren
– Dhiren, Commented Aug 21, 2018 at 17:37
Why would the return look like this when you have empty results in id:1? I am confused. You result only has id: 2? — Akrion
– Akrion, Commented Aug 21, 2018 at 18:53

Akrion · Accepted Answer · 2018-08-21 18:35:15Z

3

This should do it:

const body = [ {id: 1,courses: [{title:"course1.1", results:[{title:"result1.1.1"}, {title:"result1.1.2"}]}, {title:"course1.2", results:[]}]}, {id: 2,courses: [{title:"course1.1", results:[]}, {title:"course1.2",results:[]}]}, {id: 3,courses: []}];

console.log(body.reduce((r,c) => (c.courses.length ? r.push({ id: c.id, courses: [...c.courses.filter(({results}) => !results.length)]}) : true) && r, []))

It uses reduce and a filter to get what you need.

Update: Added handling in the case where courses is just an empty array with no results e.g. {id: 3,courses: []}.

edited Aug 21, 2018 at 18:35

answered Aug 21, 2018 at 17:32

Akrion

18.6k1 gold badge38 silver badges58 bronze badges

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

9 Comments

Jonathan Lafleur Over a year ago

It's almost working, it's removing the first level of information, so I now receive just the courses with no parent id.

Akrion Over a year ago

Oh you mean you need the id?

Jonathan Lafleur Over a year ago

I added expected value in the question so you can see what I'm expecting :) Thank you for your help !

Jonathan Lafleur Over a year ago

I just ran into an error, if the parent has no course with result, it still return the parent with an empty result, is there a way to get rid of it ?

const body = [{id: 1, courses: [{title: "course1.1", results: []}, {title: "course1.2", results: []}]}, {id: 2, courses: [{title: "course1.1", results: []}, {title: "course1.2", results: []}]}];

Akrion Over a year ago

Sure give me a few mins

|

Nina Scholz · Accepted Answer · 2018-08-21 17:42:07Z

1

You could map new objects without mutating the original data.

var array = [{ id: 1, courses: [{ title: "course1.1", results: [{ title: "result1.1.1" }, { title: "result1.1.2" }] }, { title: "course1.2", results: [] }] }, { id: 2, courses: [{ title: "course1.1", results: [] }, { title: "course1.2", results: [] }] }],
    result = array.map(o => 
        Object.assign(
            {},
            o,
            { courses: o.courses.filter(({ results: { length } }) => !length) }
        )
    );	
    
console.log(result);

answered Aug 21, 2018 at 17:42

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

1 Comment

Jonathan Lafleur Over a year ago

Thanks for your answer @Nina :)

Ryan Z · Accepted Answer · 2018-08-21 18:00:10Z

-1

    const body = [
    {id: 1,courses: [{title:"course1.1", results:[{title:"result1.1.1"}, {title:"result1.1.2"}]}, {title:"course1.2", results:[]}]},
    {id: 2,courses: [{title:"course1.1", results:[]}, {title:"course1.2",results:[]}]},   
    ];    
    let results = body.find(session => -1 < session.courses.findIndex(course => course.results.length <=0))
    console.log(results)

Array.find() documentation Array.findIndex()

edited Aug 21, 2018 at 18:00

answered Aug 21, 2018 at 17:52

Ryan Z

704 bronze badges

Collectives™ on Stack Overflow

Getting first item in an array with a specific parameter empty

3 Answers 3

9 Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

9 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related