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Array : Object
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An array is an ordered list of elements.

Platform Support

IE Mozilla Netscape Opera Safari
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Constructors

Constructor Action IE Mozilla Netscape Opera Safari
Array Constructor(Number arrayLength, Number elementN) : Array
Constructs a new instance of an array.
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Properties

Property Action IE Mozilla Netscape Opera Safari
constructor : Object
Specifies the function that creates the Array prototype.
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index : Number
Zero-based index number for the corresponding string in a RegExp match.
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input : String
String in a RegExp match.
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length : Number
Integer specifying the number of elements in an array.
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prototype : Object
Represents the Array prototype object.
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Functions

Method Action IE Mozilla Netscape Opera Safari
concat(Number valueN) : Array
Returns a new array comprised of this array joined with other array(s) and/or value(s).
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every(Function callback, Function thisObject) : Boolean
Returns true if every element in an array meets the specified criteria.
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filter(Function callback, Function thisObject) : Array
Creates a new array with all elements that meet the specified criteria.
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forEach(Function callBack, Object thisObject) : Object
Executes the specified function once for each element in an array.
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indexOf([Object searchElement,] [Number fromIndex]) : Number
Returns the first index number at which the specified element can be found in the array. Returns -1 if the element is not present.
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join([String separator]) : String
Joins all elements of an array into a string.
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lastIndexOf([Object searchElement,] [Number fromIndex]) : Number
Searches an array backwards starting from fromIndex and returns the last index number at which the specified element can be found in the array. Returns -1 if the element is not present.
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map(Function callBack, Object thisObject) : Array
Creates a new array with the results of calling a provided function on every element in this array.
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pop() : Object
Removes the last element from an array and returns that element. This method changes the length of the array.
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push(Object element1, ..., elementN) : Number
Adds one or more elements to the end of an array and returns the new length of the array. This method changes the length of the array.
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reverse() : Array
Transposes the elements of an array: the first array element becomes the last and the last becomes the first.
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shift() : Object
Removes the first element from an array and returns that element. This method changes the length of the array.
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slice(Object begin, Object end) : Array
Extracts a section of an array and returns a new array.
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some([Object searchElement,] [Number fromIndex]) : Boolean
Returns true if some element in the array passes the test implemented by the provided function.
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sort([Function compareFunction]) : Array
Sorts the elements of an array.
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splice(Object index, [Number howMany,] Object element1, ..., elementN) : Array
Returns the array with the specified elements inserted or removed.
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toLocaleString() : String
Returns a localized string version of the array.
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toSource() : String
Returns a string representing the source code of the array.
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toString() : String
Returns a string representing the specified array and its elements.
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unshift(Object element1, ..., elementN) : Number
Adds one or more elements to the beginning of an array and returns the new length of the array.
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valueOf() : Boolean|Number|String
Returns the primitive value of an array or the primitive value of its elements.
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Creating an Array

The following example creates an array, msgArray, with a length of 0, then assigns values to msgArray[0] and msgArray[99], changing the length of the array to 100.

var msgArray = new Array();
         msgArray[0] = "Hello";
         msgArray[99] = "world";
         // The following statement is true,
         // because defined msgArray[99] element.
         if (msgArray.length == 100)
         myVar = "The length is 100.";

Creating a Two-dimensional Array

The following creates a two-dimensional array and assigns the results to myVar.

var myVar = "Multidimensional array test; ";
         a = new Array(4);
         for (var i = 0; i < 4; i++) {
         a[i] = new Array(4);
         for (var j = 0; j < 4; j++) {
         a[i][j] = "[" + i + "," + j + "]";
         }
         }
         for (var i = 0; i < 4; i++) {
         str = "Row " + i + ":";
         for (var j = 0; j < 4; j++) {
         str += a[i][j];
         }
         myVar += str + "; ";
         }

The following string is assigned to myVar (line breaks are used here for readability):

Multidimensional array test;
         Row 0: [0,0][0,1][0,2][0,3];
         Row 1: [1,0][1,1][1,2][1,3];
         Row 2: [2,0][2,1][2,2][2,3];
         Row 3: [3,0][3,1][3,2][3,3];

Remarks

An array is an ordered set of values associated with a single variable name.

The following example creates an Array object with an array literal; the coffees array contains three elements and has a length of three:

coffees = ["French Roast", "Columbian", "Kona"];

You can construct a dense array of two or more elements starting with index 0 if you define initial values for all elements. A dense array is one in which each element has a value. The following code creates a dense array with three elements:

myArray = new Array("Hello", myVar, 3.14159);

Indexing an array

You index an array by its ordinal number. For example, assume you define the following array:

myArray = new Array("Wind", "Rain", "Fire");

You can then refer to the elements as thus:

Specifying a single parameter

When you specify a single numeric parameter with the Array constructor, you specify the initial length of the array. The following code creates an array of five elements:

billingMethod = new Array(5);

The behavior of the Array constructor depends on whether the single parameter is a number.

The following code creates an array of length 25, then assigns values to the first three elements:

musicTypes = new Array(25);
            musicTypes[0] = "R&B";
            musicTypes[1] = "Blues";
            musicTypes[2] = "Jazz";

Increasing the array length indirectly

An array's length increases if you assign a value to an element higher than the current length of the array. The following code creates an array of length 0, then assigns a value to element 99. This changes the length of the array to 100.

colors = new Array();
            colors[99] = "midnightblue";

Creating an array using the result of a match

The result of a match between a regular expression and a string can create an array. This array has properties and elements that provide information about the match. An array is the return value of RegExp.exec, String.match, and String.replace. To help explain these properties and elements, look at the following example and then refer to the table below:

// Match one d followed by one or more b's followed by one d
            // Remember matched b's and the following d
            // Ignore case
            
            myRe = /d(b+)(d)/i;
            myArray = myRe.exec("cdbBdbsbz");

The properties and elements returned from this match are as follows:

Property/Element Description Example
input A read-only property that reflects the original string against which the regular expression was matched. cdbBdbsbz
index A read-only property that is the zero-based index of the match in the string. 1
[0] A read-only element that specifies the last matched characters. dbBd
[1], ...[n] Read-only elements that specify the parenthesized substring matches, if included in the regular expression. The number of possible parenthesized substrings is unlimited. [1]: bB
[2]: d

Availability

JavaScript 1.1|JScript 2.0|ECMAScript v1

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