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5 Useful Array Methods in Javascript

Aya Bouchiha
Full stack web developer
・2 min read

Hi, I'm Aya Bouchiha today, I'm going to talk about useful Array methods in Javascript.

every

every(callbackFunction): returns true if all elements in an array pass a specific test, otherwise, returns false

const allProductsPrices = [21, 30, 55, 16, 46];
// false because of 16 < 20
const areLargerThanTwenty = allProductsPrices.every(
    (productPrice) => productPrice > 20
);
// true because allProductsPrices < 60
const areLessThanSixty = allProductsPrices.every(
    (productPrice) => productPrice < 60
);
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some

some(callbackFunction): returns true if at least one element in the array passes a giving test, otherwise, it returns false.

const allProductsPrices = [10, 0, 25, 0, 40];
const isThereAFreeProduct = allProductsPrices.some(
    (productPrice) => productPrice === 0
);
const isThereAPreciousProduct = allProductsPrices.some(
    (productPrice) => productPrice > 100
);
console.log(isThereAFreeProduct); // true
console.log(isThereAPreciousProduct); // false
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fill

fill(value, startIndex = 0, endIndex = Array.length) : fills specific elements in an array with a one giving value.

const numbers = [20, 254, 30, 7, 12];
console.log(numbers.fill(0, 2, numbers.length)); // [ 20, 254, 0, 0, 0 ]

// real example
const emailAddress = "developer.aya.b@gmail.com";
const hiddenEmailAddress = emailAddress.split("").fill("*", 2, 15).join("");
console.log(hiddenEmailAddress); // de*************@gmail.com
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reverse

reverse(): this method reverses the order of the elements in an array.

const descendingOrder = [5, 4, 3, 2, 1];
// ascendingOrder
console.log(descendingOrder.reverse()); // [ 1, 2, 3, 4, 5 ]
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includes

includes(value, startIndex = 0): is an array method that returns true if a specific value exists in a giving array, otherwise, it returns false (the specified element is not found).

const webApps = ["coursera", "dev", "treehouse"];
console.log(webApps.includes("dev")); // true
console.log(webApps.includes("medium")); // false
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Summary

  • every(callbackFunction): returns true if all elements in an array passed a giving test.
  • some(callbackFunction): returns true if at least one element passed a giving test.
  • fill(value, startIdx = 0, endIdx = arr.length): fills specified array elements with a giving value.
  • reverse(): reverses the order of the elements in an array.
  • includes(value, startIdx = 0): check if a giving value exist in an specific array

References

Have a nice day!

Discussion (2)

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Flagmans

Very useful. Thank you.

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Aya Bouchiha Author

You're always welcome !