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How to iterate array in JavaScript ES6

for loop

for loop can iterate through the elements of an array as below example:

let directions = ["north", "south", "east", "west"];

for(let i=0; i<3; i++) {

   console.log(directions[i]);

}

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for..in loop

In for..in loop, the loop iterator takes the numeric index of the loop iteration, starting with 0.

Example:

let directions = ["north", "south", "east", "west"];

for(let i in directions) {

   console.log(directions[i]);

}

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for..of loop

In for..of loop, the loop iterator takes the each value of the array one after the other, starting with first element.

Example:

let directions = ["north", "south", "east", "west"];

for(let i of directions) {

   console.log(i);

}

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JavaScript ES6 Array methods

 

Methods

Description

Example

Array.from()

It converts array-like values and iterable values into arrays.

const myArr = Array.from("ABCDEFG");

console.log(myArr);

Output:  ['A', 'B', 'C', 'D', 'E', 'F', 'G']

find()

It finds a value from an array, based on the specific criteria that are passed to this method.

const numbers = [4, 9, 18, 50, 60];

let first = numbers.find(myFunction);

function myFunction(value, index, array) {

  return value > 20;

}

console.log(first);
Output:

50

 

findIndex()

The findIndex() returns the index of the first element of the given array that satisfies the given condition.

const numbers = [4, 9, 18, 50, 60];

let first = numbers.findIndex(myFunction);

function myFunction(value, index, array) {

  return value > 20;

}

console.log(first);
Output:

3

 

keys()

It returns an array iterator object along with the keys of the array.

const fruits = ["Banana", "Orange", "Apple", "Mango"];

const keys = fruits.keys();

for (let x of keys) {

  console.log(x);

}

Output:  

0

1

2

3

 

 

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