JavaScript - L'objet Arrays

le Arrayobject vous permet de stocker plusieurs valeurs dans une seule variable. Il stocke une collection séquentielle à taille fixe d'éléments du même type. Un tableau est utilisé pour stocker une collection de données, mais il est souvent plus utile de considérer un tableau comme une collection de variables du même type.

Syntaxe

Utilisez la syntaxe suivante pour créer un Array objet -

var fruits = new Array( "apple", "orange", "mango" );

le Arrayparamètre est une liste de chaînes ou d'entiers. Lorsque vous spécifiez un paramètre numérique unique avec le constructeur Array, vous spécifiez la longueur initiale du tableau. La longueur maximale autorisée pour un tableau est de 4 294 967 295.

Vous pouvez créer un tableau en attribuant simplement des valeurs comme suit -

var fruits = [ "apple", "orange", "mango" ];

Vous utiliserez des nombres ordinaux pour accéder et définir des valeurs à l'intérieur d'un tableau comme suit.

fruits[0] is the first element
fruits[1] is the second element
fruits[2] is the third element

Propriétés du tableau

Voici une liste des propriétés de l'objet Array avec leur description.

N ° Sr. Propriété et description
1 constructor

Returns a reference to the array function that created the object.
2

index

The property represents the zero-based index of the match in the string
3

input

This property is only present in arrays created by regular expression matches.
4 length

Reflects the number of elements in an array.
5 prototype

The prototype property allows you to add properties and methods to an object.

In the following sections, we will have a few examples to illustrate the usage of Array properties.

Array Methods

Here is a list of the methods of the Array object along with their description.

Sr.No. Method & Description
1 concat()

Returns a new array comprised of this array joined with other array(s) and/or value(s).
2 every()

Returns true if every element in this array satisfies the provided testing function.
3 filter()

Creates a new array with all of the elements of this array for which the provided filtering function returns true.
4 forEach()

Calls a function for each element in the array.
5 indexOf()

Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found.
6 join()

Joins all elements of an array into a string.
7 lastIndexOf()

Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found.
8 map()

Creates a new array with the results of calling a provided function on every element in this array.
9 pop()

Removes the last element from an array and returns that element.
10 push()

Adds one or more elements to the end of an array and returns the new length of the array.
11 reduce()

Apply a function simultaneously against two values of the array (from left-to-right) as to reduce it to a single value.
12 reduceRight()

Apply a function simultaneously against two values of the array (from right-to-left) as to reduce it to a single value.
13 reverse()

Reverses the order of the elements of an array -- the first becomes the last, and the last becomes the first.
14 shift()

Removes the first element from an array and returns that element.
15 slice()

Extracts a section of an array and returns a new array.
16 some()

Returns true if at least one element in this array satisfies the provided testing function.
17 toSource()

Represents the source code of an object
18 sort()

Sorts the elements of an array
19 splice()

Adds and/or removes elements from an array.
20 toString()

Returns a string representing the array and its elements.
21 unshift()

Adds one or more elements to the front of an array and returns the new length of the array.

In the following sections, we will have a few examples to demonstrate the usage of Array methods.