7 JavaScript Array Methods You Should Know

In JavaScript, the array data type consists of a list of elements. JavaScript developers can work with arrays using a variety of built-in methods. In previous articles, we covered the most commonly used javascript array methods. In this article, we will cover important javascript array methods that every developer should be aware of.

Map ( )

The map() method performs a specified function on each element of an array and returns a new array. The map calls a provided callback function once for each element in an array in the specified order and then creates a new array from the results. Only array indexes with assigned values, including undefined ones, are triggered by a callback.

var array1 = [2, 4, 6, 8];

// pass a function to map
const map1 = array1.map(function(x) {
 return x * 2
});

console.log(map1);

OUTPUT

[4, 16, 36, 64]

Reduce ( )

In javascript, the reduce() method applies a function to the accumulator and each element in the array from left to right to reduce it to a single output value.

const text = ["React ", "is ", "scalable"];

// function to join each string element

function joinStrings(accumulator, currentValue) {
  return accumulator + currentValue;
}

let joinedString = text.reduce(joinStrings);

console.log(joinedString);

OUTPUT:

React is scalable

Array.from ( )

In javascript, the array. From ( ) method creates a new shallow copy from an array or from an array-like iterable object.

// creating a new array by using a string

let newArray = Array.from("axios");

console.log(newArray);

OUTPUT:

[ 'a',‘x’,’i’,’o’,’s’ ]

some( )

In JavaScript provided Some ( ) function is used to determine whether at least one element in the array passes the test.

// This is a test function that returns an odd number.
function isOdd(element) {

    return element % 3 === 0;
  }

  // Array definition
  let numbers = [11, 13, 12, 16, 14];

  // determines whether the numbers array contains at least one odd number
  console.log(numbers.some(isOdd));

OUTPUT:

true

Every( ) :

The every( ) method in Javascript helps to ensure that all elements in an array pass the test implemented by the provided function.

 function isBelowThreshold(currentValue) {
  return currentValue < 40;
}

var array1 = [1, 10, 19, 47, 10, 13];

console.log(array1.every(isBelowThreshold));

OUTPUT :

False

Every method calls the provided callback function once for each array element until it finds one that returns a false value. If such an element is discovered, all methods return false right away. Otherwise, every return is true if the callback returns true for all elements.

Includes( )

In javascript, the includes() method checks whether an array contains a specified element or not. The includes() method returns a Boolean value, and by the end of the operations, it returns whether it's true or false.

let languages = ["JavaScript", "React", "Vue"];

// checking whether the array contains 'Vue'

let check = languages.includes("Vue");

console.log(check);

OUTPUT:

True

flat( ) :

In Javascript, flat() method creates a new array by flattening a nested array up to the specified depth.

let data = [11, 12, [13, 14, [15, 16, [17, 18]]]];

let flattenArray = data.flat(1);

console.log(flattenArray);

OUTPUT:

[ 11, 12, 13, 14, [ 15, 16, [ 17, 18 ] ] ]

Conclusion:

As we discussed, those mentioned above are some of the essential JavaScript Array Methods a developer should know.

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