Javascript remove null from object

Question

I'm having afunction that is merging two arrays like this:

var sorting = data.genre.map((i) => data_info.find((o) => o.id === i));

The problem in this function is if it couldn't find genre in data_info it adds null to the object arra and therefore my function fails.
So the question is: How could I remove in above single line all values that are null?

I get this output from thr line above:

[{"id":1,"category":"Action"},{"id":2,"category":"Adventure"},null]

And need to get this:

[{"id":1,"category":"Action"},{"id":2,"category":"Adventure"}]

I tried to add && data_info(o) !== null to the line above but I get null in the object array anyway.

Add a `filter` to the output of `map`. `data.genre.map((i) => data_info.find((o) => o.id === i)).filter((i) => return i != null );` — gurvinder372, Oct 11 '17 at 07:52
The map function applies the operation on each item of the array and returns an array with exactly the same number of elements as in the input array. — ajaysinghdav10d, Oct 11 '17 at 07:54
Possible duplicate of [How to remove item from array by value?](https://stackoverflow.com/questions/3954438/how-to-remove-item-from-array-by-value) — Nikola Lukic, Oct 11 '17 at 08:13

Karim · Accepted Answer · 2017-12-01T14:14:27.827

2

change .map to .filter

var sorting = data.genre.filter((i) => data_info.find((o) => o.id === i) ? true : false);

edited Dec 01 '17 at 14:14

answered Oct 11 '17 at 07:54

Karim

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Mihai Alexandru-Ionut · Answer 2 · 2017-10-11T07:59:25.503

1

You can use filter method by passing a callback provided function.

var sorting = data.genre.map((i) => data_info.find((o) => o.id === i)).filter(function(item){
    return item!=null;
});

edited Oct 11 '17 at 07:59

answered Oct 11 '17 at 07:54

Mihai Alexandru-Ionut

41,021
10
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score 1 · Answer 3 · answered Oct 11 '17 at 07:54

You can filter the result of your map function to remove null.

var sorting = data.genre.map((i) => data_info.find((o) => o.id === i)).filter(item => {
   return item !== null;
});

The filter() method creates a new array with all elements that pass the test implemented by the provided function.

Javascript remove null from object

3 Answers3