How to filter undefined value in javascript arrays?

Question

const values = dataSku.map(sku => {return map.skuInfo[sku].description})

Here, there is some posibility that map.skuInfo[sku] can be null/undefined and I need to filter it. How would it be possible ?

Array.prototype.filter() (link: MDN) - e.g. const myFilteredArray = myArray.filter(Boolean) (don't necessarily use Boolean like I show but provide an actual comparison, even though that works filtering out "falsy" values) — Mörre
– Mörre, Commented May 23, 2018 at 20:21
Can it be other falsey values, or specifically undefined? — deceze
– deceze ♦, Commented May 23, 2018 at 20:21

Tom Con · Accepted Answer · 2018-05-23 20:23:41Z

13

Sounds like you want .filter. It's a higher order function like .map.

const values = dataSku
    .filter(item => item.description !== undefined)

I'm not sure your exact data structure but check it out here! It filters out all non-truthy return values.

answered May 23, 2018 at 20:23

Tom Con

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Comments

Vivek · Accepted Answer · 2018-05-23 20:24:28Z

2

This will solve your problem -

const values = dataSku.map(sku => map.skuInfo[sku]}).filter(skuInfo => typeof skuInfo !== "undefined").map(skuInfo => skuInfo.description);

answered May 23, 2018 at 20:24

Vivek

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Comments

Zac · Accepted Answer · 2018-05-23 20:32:08Z

1

Can be done like this:

const values = dataSku.map(sku => {
    if (!map.skuInfo[sku]) return;
    return map.skuInfo[sku].description
})

Will return out of the function if map.skuInfo[sku] is falsey.

edited May 23, 2018 at 20:32

answered May 23, 2018 at 20:25

Zac

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Comments

Dhruv Pal · Accepted Answer · 2022-06-27 07:58:44Z

0

You can something like as under

const filterNotNullAndUndefined = (sku)  => (sku?.description !== null  && sku?.description !== undefined);
const filterNotNUllAndUndefinedAndNonEmpty = (sku) => (sku?.description)

const sku = [
    {id: 1, 'description': '1'},
    {id: 2, 'description': null},
    {id: 3, 'description': undefined},
    {id: 4, 'description': ''},
    null,
    undefined
];

const result1 = sku?.filter(filterNotNUllAndUndefinedAndNonEmpty);
const result2 = sku?.filter(filterNotNullAndUndefined);

console.log(result1);
console.log(result2);

edited Jun 27, 2022 at 7:58

answered Jun 27, 2022 at 5:32

Dhruv Pal

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2 Comments

eroironico Over a year ago

filterNotNullAndUndefined could be shorter: sku => sku?.description ?? false

Dhruv Pal Over a year ago

oh yes totally missed Nullish coalescing operator (??)

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