JavaScript-配列オブジェクト

ザ・ Arrayオブジェクトを使用すると、1つの変数に複数の値を格納できます。同じタイプの要素の固定サイズの順次コレクションを格納します。配列はデータのコレクションを格納するために使用されますが、配列を同じタイプの変数のコレクションと考える方が便利な場合がよくあります。

構文

次の構文を使用して、 Array オブジェクト-

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

ザ・ Arrayパラメータは、文字列または整数のリストです。Arrayコンストラクターで単一の数値パラメーターを指定するときは、配列の初期長を指定します。配列に許可される最大長は4,294,967,295です。

次のように値を割り当てるだけで配列を作成できます-

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

次のように、序数を使用して配列内の値にアクセスし、値を設定します。

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

配列のプロパティ

これは、Arrayオブジェクトのプロパティとその説明のリストです。

シニア番号	プロパティと説明
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.