ES6 introduced new array functions to simplify the iteration and filtering the array of elements or objects.

Let’s discuss about new methods introduced in ES6 language

Array Of function in javascript

Till now, we can create arrays using array literal syntax or Array object

// Array declaration in ES5

// Literal Syntax
var numbers = [1, 2, 3,4,5]
console.log(numbers);

console.log(numbers.length);
// Array Constructor
let words = Array("one","two");
console.log(words.length);
console.log(words);

Output:

[ 1, 2, 3, 4, 5 ]
5
2
[ 'one', 'two' ]

ES6 introduced new of creating an array using of method, used create an array of variable arguments items.

// Array of method
let words = Array.of("one","two");
console.log(words.length);
console.log(words);

Output:

2
[ 'one', 'two' ]

Array from function in ES6

array.from() method used to creat an array from an iterable object with applying callback function applied to it. It is used to convert set and map into array of values.

Here is syntax

Array.from(iterableobjects, function, value)  

iterableobjects are array, set or Map objects Function - Normal or lambda expression that applies to each element value - value passed and used in function with this scope Let' see an example

var numbers = [1, 2, 3,4,5]
let result = Array.from(numbers, number => number * number);
console.log(result);

Array fill function

For example, If array wants to fill with fixed or default values.

Array.fill function used to initialize the values with values

Syntax:

Array.fill(value,[index])

default value is replaced with all values in array of elements. if index is given,Only updates specific element at index position.

var numbers = [1, 2, 3,4,5]
numbers.fill(0);
console.log(numbers);
numbers.fill(0,1);
console.log(numbers);

Output:

[ 0, 0, 0, 0, 0 ]
[ 1, 0, 0, 0, 0 ]

Array foreach function

foreach function used to iterate each element and execute a function for each function.

Syntax

forEach(callbackfunction,[arguments])

callbackfunction is a javascript function that accepts three arguments

  • value - Current value
  • index - current index
  • originalarray - array to iterate

Here is an example

var numbers = [1, 2, 3,4,5]

// normal function
function show(item) {
  console.log(item)
}
numbers.forEach(show)

// function expression
const display=function(item,index) {
  console.log(item+" - "+index)
}
numbers.forEach(display)

// arrow or lambda expression
const print=(item,index,numbers)=> {
  console.log(item+" - "+index,numbers)
}
numbers.forEach(print)

Output:

1
2
3
4
5
1 - 0
2 - 1
3 - 2
4 - 3
5 - 4
1 - 0 [ 1, 2, 3, 4, 5 ]
2 - 1 [ 1, 2, 3, 4, 5 ]
3 - 2 [ 1, 2, 3, 4, 5 ]
4 - 3 [ 1, 2, 3, 4, 5 ]
5 - 4 [ 1, 2, 3, 4, 5 ]

Other methods

There are some other methods

  • Array.prototype.values()
  • Array.prototype.keys()
  • Array.prototype.entries()
  • Array.prototype.findIndex()
  • Array.prototype.find()
  • Array.prototype.copyWithin()
  • Array.prototype.fill()