Returning the index of an empty element inside an array

Question

So I have an array let's say :

var arr = ['apples' , 'cherries' , 'strawberries']

and after so much coding, I get hungry so I eat the 'cherries' so now I have

arr = ['apples',null,'strawberries']

So I was wondering if there is some sort of JavaScript function that can return the first null element inside an array ?

Let's say for instance my grandma gives me 'potatoes' and I want to add them inside the null space I have like a good boy I am, and I need the index of that null element so I may know where to place my sweet goods from grandma.

Is this a sort of problem taken from a course of javascript? Take a look to Array.findIndex() — Shidersz
– Shidersz, Commented May 30, 2019 at 0:21
No it is not. I want to push some data in firebase with specific indexes, (1 , 2 , 3 ,4 so on ) and If I delete an element it becomes null, and I want to put the new data inside there instead of putting it at the end of the array with some wierd id that firebase generates. — Ionut Eugen
– Ionut Eugen, Commented May 30, 2019 at 0:23
The real question is why would you eat the cherries when you have the option of delicious strawberries or the full tasty meal of a giant Honeycrisp apple? — Scott Sauyet
– Scott Sauyet, Commented May 30, 2019 at 22:35

Xavier Brassoud · Accepted Answer · 2019-05-30 00:31:20Z

1

From W3C documentation :

arr.findIndex(element => element === null);

Replace :

arr[arr.findIndex(element => element === null)] = "potatoes";

answered May 30, 2019 at 0:31

Xavier Brassoud

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1 Comment

Ionut Eugen Over a year ago

This is actually what I was looking for :D Thanks

Akrion · Accepted Answer · 2019-05-30 00:45:29Z

1

Since null is a falsy value you can simply use Array.findIndex and match on falsy values:

var arr = ['apples',null,'strawberries']

let index = arr.findIndex(x => !x)

console.log(index)
console.log(arr[index])

answered May 30, 2019 at 0:45

Akrion

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Comments

JeremyW · Accepted Answer · 2019-05-30 01:40:47Z

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try removing the element using below code :

var arr = ['apples' , 'cherries' , 'strawberries'];

arr.splice(1,1);

and remove and add try :

var arr = ['apples' , 'cherries' , 'strawberries'];

arr.splice(1,1, 'potatoes');

edited May 30, 2019 at 1:40

JeremyW

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answered May 30, 2019 at 0:30

Guilherme Geraldo

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1 Comment

Ionut Eugen Over a year ago

Yes, however I don't know the index of the null element so I cant splice on it :/

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