JavaScript - The Arrays Object

The Array object lets you store multiple values in a single variable. It stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.

Syntax

Use the following syntax to create an Array object −

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

The Array parameter is a list of strings or integers. When you specify a single numeric parameter with the Array constructor, you specify the initial length of the array. The maximum length allowed for an array is 4,294,967,295.

You can create array by simply assigning values as follows −

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

You will use ordinal numbers to access and to set values inside an array as follows.

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

Array Properties

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

Sr.No.	Property & 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() 提取数组的一部分并返回一个新数组。
16	一些（）如果此数组中至少有一个元素满足提供的测试函数，则返回 true。
17 号	源（）代表对象的源代码
18	种类（）对数组的元素进行排序
19	拼接（）添加和/或删除数组中的元素。
20	toString() 返回表示数组及其元素的字符串。
21	取消移位（）将一个或多个元素添加到数组的前面并返回数组的新长度。

在下面的部分中，我们将通过一些示例来演示数组方法的用法。