Integration of the array. / JavaScript

# Web Site Writing Basics

# javascript

# array

There are many ways to include Array in JavaScript, depending on what you want to include and whether you want to use new features of the language. The most popular methods are as follows:

1. Using Spread Syntax (...) (Recommended method)

This is the most modern and simple method for combining Array in JavaScript.

JavaScript

const arr1 = [1, 2, 3];

const arr2 = [4, 5, 6];

/ / Combine arr1 and arr2 in a new Array.

Const combinedArray = [...Arr1,...Arr2];

console.log (combinedArray);

/ / Results: [1, 2, 3, 4, 5, 6]

Advantages: Short, easy to read, and create a new Array without changing the original Array (immutable).

Applicable to: ES6 (ECMAScript 2015) and above

2. Use of the concat () method

The concat () method is a traditional way to combine Arrays. It will create a new Array with a member of the Array being invoked and an Array being sent as an Argument.

JavaScript

const arr1 = ['a', 'b'];

const arr2 = ['c', 'd'];

const arr3 = ['e', 'f'];

/ / Multiple Arrays can be included.

const combinedArray = arr1.concat (arr2, arr3);

console.log (combinedArray);

/ / Result: ['a', 'b', 'c', 'd', 'e', 'f']

Advantages: Works with all versions of JavaScript and creates a new Array as well.

3. Use of the push () method in conjunction with Spread Syntax (...)

If you want to combine the second Array with the first Array that already exists (namely editing the first Array), you can use push () in conjunction with Spread Syntax.

JavaScript

Const existingArray = [10, 20];

const newElements = [30, 40];

/ / Push all members of newElements into the existingArray.

Existing Array. Push (...News Elements);

Console.log (existingArray);

/ / Results: [10, 20, 30, 40]

Caution: This method is a mutate of the original Array.

4.Use of Reduce () (for Array integration of Array)

If you have an Array that consists of sub-Arrays and want to combine every one of those sub-Arrays into a single Array (Flattening),

JavaScript

Const arrayOfArrays = [

[1, 2],

[3, 4],

[5, 6]

];

Const combinedArray = arrayOfArrays.reduce (accumulator, currentArray) = > {

Return accumulator. Concat (currentArray);

}, []); / / Beginning with an empty Array []

console.log (combinedArray);

/ / Results: [1, 2, 3, 4, 5, 6]

Simpler alternative: For combining sub-Arrays in a given depth (e.g. 1 layer deep), you can use the flat () method:

JavaScript

const arrayOfArrays = [[1, 2], [3, 4], [5, 6]];

const combinedArray = arrayOfArrays.flat (); / / does not require reduction ()

/ / Results: [1, 2, 3, 4, 5, 6]