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Cover image for I'll teach you 7 Array methods. (with animations!)
Fredy Sandoval
Fredy Sandoval

Posted on • Updated on • Originally published at fredy.dev

I'll teach you 7 Array methods. (with animations!)

map

Creates a new array populated with the results of a provided function on every element.

[1, 2, 3].map( n => n * 2 ); // [2, 4, 6]
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11

filter

Creates a Copy of a portion of a given array, filtered down to just the elements from the given array that pass the test, keep in mind that changes of your first array will affect your copy.

[1,2,3].filter( n => n !== 2 ); // [1,3]
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22

find

Stops and returns the first element in the provided array that satisfies the provided testing function, otherwise returns undefined.

[1,2,3].find( n => n == 2 ) // 2
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33

findIndex

Returns the index of the first element that satisfies the provided testing function. Otherwise -1 is returned.

[1,2,3].findIndex( n => n == 2) // 1
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44

fill

Changes all elements in an array to a static value, from a start index (default 0) to an end index (default array.length). It returns the modified array.

[1,2,3].fill('Txt', 1,2) // [1,'Txt', 3]
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77

every

Tests all elements in the array. After finished returns a Boolean value

[2,2,2].every( n => n == 2 ) // true
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88

some

Tests whether at least one element in the array passes the test implemented by the provided function.

[1,2,3].some( n => n == 2) // true
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99

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Top comments (18)

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matijanovosel profile image
Matija Novosel • Edited on

The code for every has the wrong array I think. Otherwise, a great way of explaining things!

Image description

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davido242 profile image
Monday David S.

I don't really get the point here pls!
I was thinking this is another version of the example for the every method and atleast the result should be false since not every item is equal to 2.

Got confused with the result of this.answer though!

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matijanovosel profile image
Matija Novosel

It had the wrong code initially but the author was diligent enough to change it afterwards.

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davido242 profile image
Monday David S.

Alright super!!

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fredysandoval profile image
Fredy Sandoval Author

Thanks for pointing out.

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tracygjg profile image
TGJ Gilmore

Fredy,
Nice article - love the animation but I think it could do with two examples for the every and some methods to demonstrate complete and early exit.

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jacksonkasi profile image
Jackson Kasi

I like teach with animation!

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themfon profile image
Mfon.

Very engaging. I love the gifs

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codewithtee profile image
Tabassum Khanum

Very Helpful!

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hasobi profile image
Hasobi

excellent content! love it!

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said_mounaim profile image
Said Mounaim

Usefull! Thanks for sharing

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svdoever profile image
Serge van den Oever

Nice way of explaining!

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rabeeh profile image
Rabeeh Ebrahim

Thanks for creating this. Nice content.

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chiki1601 profile image
Miss Pooja Anilkumar Patel

Cool

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jmfayard profile image
Jean-Michel Fayard πŸ‡«πŸ‡·πŸ‡©πŸ‡ͺπŸ‡¬πŸ‡§πŸ‡ͺπŸ‡ΈπŸ‡¨πŸ‡΄

How did you produce those animations ?
Such a great teaching tool

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acarrasco profile image
Alfonso Carrasco

Felicidades, increΓ­ble explicaciΓ³n!!!

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ruleenugroho profile image
ruleenugroho

very usefull, Thanks

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simmbiote profile image
JBS

Pretty neat. The gif for .fill is not quite right.

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