Array Object (JavaScript)

Provides support for creation of arrays of any data type.

Syntax

arrayObj = new Array()  
arrayObj = new Array([size])  
arrayObj = new Array([element0[, element1[, ...[, elementN]]]])  

Parameters

arrayObj
Required. The variable name to which the Array object is assigned.

size
Optional. The size of the array. As arrays are zero-based, created elements will have indexes from zero to size -1.

element0,...,elementN
Optional. The elements to place in the array. This creates an array with n + 1 elements, and a length of n + 1. Using this syntax, you must supply more than one element.

Remarks

After an array is created, you can access the individual elements of the array by using [ ] notation. Note that arrays in JavaScript are zero-based.

var my_array = new Array();  
for (i = 0; i < 10; i++) {  
    my_array[i] = i;  
}  
x = my_array[4];  
document.write(x);  

// Output: 4  

You can pass an unsigned 32-bit integer to the Array constructor to specify the size of the array. If the value is negative or not an integer, a run-time error occurs. If you run the following code, you should see this error in the Console.

var arr = new Array(10);  
document.write(arr.length);  

// Output: 10  

// Don't do this  
var arr = new Array(-1);  
arr = new Array(1.50);   

If a single value is passed to the Array constructor, and it is not a number, the length property is set to 1, and the value of the only element becomes the single, passed-in argument.

var arr = new Array("one");  
document.write(arr.length);  
document.write("<br/>");  
document.write(arr[0]);  

// Output:  
1  
one  

JavaScript arrays are sparse arrays, which means that not all the elements in an array may contain data. In JavaScript, only the elements that actually contain data exist in the array. This reduces the amount of memory used by the array.

Requirements

Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards, Internet Explorer 11 standards. Also supported Store apps (Windows 8 and Windows Phone 8.1). See Version Information.

Some members in the following lists were introduced in later versions. For more information, see Version Information or the documentation for the individual members.

Properties

The following table lists the properties of the Array object.

Property Description
constructor Property Specifies the function that creates an array.
length Property (Array) Returns an integer value that is one higher than the highest element defined in an array.
prototype Property Returns a reference to the prototype for an array.

Functions

The following table describes the functions of the Array object.

Function Description
Array.from Function Returns an array from an array-like or iterable object.
Array.isArray Function Returns a Boolean value that indicates whether an object is an array.
Array.of Function Returns an array from the passed in arguments.

Methods

The following table lists the methods of the Array object.

Method Description
concat Method (Array) Returns a new array consisting of a combination of two arrays.
entries Method Returns an iterator that contains the key/value pairs of the array.
every Method Checks whether a defined callback function returns true for all elements in an array.
fill Method Populates an array with a specified value.
filter Method Calls a defined callback function on each element of an array, and returns an array of values for which the callback function returns true.
findIndex Method Returns an index value for the first array element that meets test criteria specified in a callback function.
forEach Method Calls a defined callback function for each element in an array.
hasOwnProperty Method Returns a Boolean value that indicates whether an object has a property with the specified name.
indexOf Method (Array) Returns the index of the first occurrence of a value in an array.
isPrototypeOf Method Returns a Boolean value that indicates whether an object exists in another object's prototype chain.
join Method Returns a String object consisting of all the elements of an array concatenated together.
keys Method Returns an iterator that contains the index values of the array.
lastIndexOf Method (Array) Returns the index of the last occurrence of a specified value in an array.
map Method Calls a defined callback function on each element of an array, and returns an array that contains the results.
pop Method Removes the last element from an array and returns it.
propertyIsEnumerable Method Returns a Boolean value that indicates whether a specified property is part of an object and whether it is enumerable.
push Method Appends new elements to an array, and returns the new length of the array.
reduce Method Accumulates a single result by calling a defined callback function for all elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
reduceRight Method Accumulates a single result by calling a defined callback function for all elements in an array, in descending order. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
reverse Method Returns an Array object with the elements reversed.
shift Method Removes the first element from an array and returns it.
slice Method (Array) Returns a section of an array.
some Method Checks whether a defined callback function returns true for any element of an array.
sort Method Returns an Array object with the elements sorted.
splice Method Removes elements from an array and, if necessary, inserts new elements in their place, returning the deleted elements.
toLocaleString Method Returns a string using the current locale.
toString Method Returns a string representation of an array.
unshift Method Inserts new elements at the start of an array.
valueOf Method Gets a reference to the array.
values Method Returns an iterator that contains the values of the array.

See Also

Scrolling, panning, and zooming sample app