String

An object representing a series of characters in a string.

Core object
Implemented in	JavaScript 1.0: Create a String object only by quoting characters. JavaScript 1.1, NES 2.0: added String constructor; added prototype property; added split method; added ability to pass strings among scripts in different windows or frames (in previous releases, you had to add an empty string to another window's string to refer to it). JavaScript 1.2, NES 3.0: added concat, match, replace, search, slice, and substr methods. JavaScript 1.3: added toSource method; changed charCodeAt, fromCharCode, and replace methods.
ECMA version	ECMA-262

Created by
The String constructor:

new String(string)

Parameters

string

Any string.

Description
The String object is a wrapper around the string primitive data type. Do not confuse a string literal with the String object. For example, the following code creates the string literal s1 and also the String object s2:

s1 = "foo" // creates a string literal value
s2 = new String("foo") // creates a String object

You can call any of the methods of the String object on a string literal value—JavaScript automatically converts the string literal to a temporary String object, calls the method, then discards the temporary String object. You can also use the String.length property with a string literal.

You should use string literals unless you specifically need to use a String object, because String objects can have counterintuitive behavior. For example:

s1 = "2 + 2" // creates a string literal value
s2 = new String("2 + 2") // creates a String object
eval(s1)     // returns the number 4
eval(s2)     // returns the string "2 + 2"

A string can be represented as a literal enclosed by single or double quotation marks; for example, "Netscape" or `Netscape'.

You can convert the value of any object into a string using the top-level String function.

Property Summary

Property	Description
constructor	Specifies the function that creates an object's prototype.
length	Reflects the length of the string.
prototype	Allows the addition of properties to a String object.

Method Summary

Method	Description
anchor	Creates an HTML anchor that is used as a hypertext target.
big	Causes a string to be displayed in a big font as if it were in a BIG tag.
blink	Causes a string to blink as if it were in a BLINK tag.
bold	Causes a string to be displayed as if it were in a B tag.
charAt	Returns the character at the specified index.
charCodeAt	Returns a number indicating the Unicode value of the character at the given index.
concat	Combines the text of two strings and returns a new string.
fixed	Causes a string to be displayed in fixed-pitch font as if it were in a TT tag.
fontcolor	Causes a string to be displayed in the specified color as if it were in a <FONT COLOR=color> tag.
fontsize	Causes a string to be displayed in the specified font size as if it were in a <FONT SIZE=size> tag.
fromCharCode	Returns a string created by using the specified sequence of Unicode values. This is a method on the String class, not on a String instance.
indexOf	Returns the index within the calling String object of the first occurrence of the specified value, or -1 if not found.
italics	Causes a string to be italic, as if it were in an I tag.
lastIndexOf	Returns the index within the calling String object of the last occurrence of the specified value, or -1 if not found.
link	Creates an HTML hypertext link that requests another URL.
match	Used to match a regular expression against a string.
replace	Used to find a match between a regular expression and a string, and to replace the matched substring with a new substring.
search	Executes the search for a match between a regular expression and a specified string.
slice	Extracts a section of a string and returns a new string.
small	Causes a string to be displayed in a small font, as if it were in a SMALL tag.
split	Splits a String object into an array of strings by separating the string into substrings.
strike	Causes a string to be displayed as struck-out text, as if it were in a STRIKE tag.
sub	Causes a string to be displayed as a subscript, as if it were in a SUB tag.
substr	Returns the characters in a string beginning at the specified location through the specified number of characters.
substring	Returns the characters in a string between two indexes into the string.
sup	Causes a string to be displayed as a superscript, as if it were in a SUP tag.
toLowerCase	Returns the calling string value converted to lowercase.
toSource	Returns an object literal representing the specified object; you can use this value to create a new object. Overrides the Object.toSource method.
toString	Returns a string representing the specified object. Overrides the Object.toString method.
toUpperCase	Returns the calling string value converted to uppercase.
valueOf	Returns the primitive value of the specified object. Overrides the Object.valueOf method.

In addition, this object inherits the watch and unwatch methods from Object.

Examples
Example 1: String literal. The following statement creates a string literal:

var last_name = "Schaefer"

Example 2: String literal properties. The following statements evaluate to 8, "SCHAEFER," and "schaefer":

last_name.length
last_name.toUpperCase()
last_name.toLowerCase()

Example 3: Accessing individual characters in a string. You can think of a string as an array of characters. In this way, you can access the individual characters in the string by indexing that array. For example, the following code displays "The first character in the string is H":

var myString = "Hello"
myString[0] // returns "H"

Example 4: Pass a string among scripts in different windows or frames. The following code creates two string variables and opens a second window:

var lastName = "Schaefer"
var firstName = "Jesse"
empWindow=window.open('string2.html','window1','width=300,height=300')

If the HTML source for the second window (string2.html) creates two string variables, empLastName and empFirstName, the following code in the first window assigns values to the second window's variables:

empWindow.empFirstName=firstName
empWindow.empLastName=lastName

The following code in the first window displays the values of the second window's variables:

alert('empFirstName in empWindow is ' + empWindow.empFirstName)
alert('empLastName in empWindow is ' + empWindow.empLastName)

anchor

Creates an HTML anchor that is used as a hypertext target.

Method of	String
Implemented in	JavaScript 1.0, NES 2.0

Syntax
anchor(nameAttribute)

Parameters

nameAttribute

A string.

Description
Use the anchor method with the document.write or document.writeln methods to programmatically create and display an anchor in a document. Create the anchor with the anchor method, and then call write or writeln to display the anchor in a document. In server-side JavaScript, use the write function to display the anchor.

In the syntax, the text string represents the literal text that you want the user to see. The nameAttribute string represents the NAME attribute of the A tag.

Anchors created with the anchor method become elements in the document.anchors array.

Examples
The following example opens the msgWindow window and creates an anchor for the table of contents:

var myString="Table of Contents"
msgWindow.document.writeln(myString.anchor("contents_anchor"))

The previous example produces the same output as the following HTML:

<A NAME="contents_anchor">Table of Contents</A>

See also
String.link

big

Causes a string to be displayed in a big font as if it were in a BIG tag.

Method of	String
Implemented in	JavaScript 1.0, NES 2.0

Syntax
big()

Parameters
None

Description
Use the big method with the write or writeln methods to format and display a string in a document. In server-side JavaScript, use the write function to display the string.

Examples
The following example uses string methods to change the size of a string:

var worldString="Hello, world"

document.write(worldString.small())
document.write("<P>" + worldString.big())
document.write("<P>" + worldString.fontsize(7))

The previous example produces the same output as the following HTML:

<SMALL>Hello, world</SMALL>
<P><BIG>Hello, world</BIG>
<P><FONTSIZE=7>Hello, world</FONTSIZE>

See also
String.fontsize, String.small

blink

Causes a string to blink as if it were in a BLINK tag.

Method of	String
Implemented in	JavaScript 1.0, NES 2.0

Syntax
blink()

Parameters
None

Description
Use the blink method with the write or writeln methods to format and display a string in a document. In server-side JavaScript, use the write function to display the string.

Examples
The following example uses string methods to change the formatting of a string:

var worldString="Hello, world"

document.write(worldString.blink())
document.write("<P>" + worldString.bold())
document.write("<P>" + worldString.italics())
document.write("<P>" + worldString.strike())

The previous example produces the same output as the following HTML:

<BLINK>Hello, world</BLINK>
<P><B>Hello, world</B>
<P><I>Hello, world</I>
<P><STRIKE>Hello, world</STRIKE>

See also
String.bold, String.italics, String.strike

bold

Causes a string to be displayed as bold as if it were in a B tag.

Method of	String
Implemented in	JavaScript 1.0, NES 2.0

Syntax
bold()

Parameters
None

Description
Use the bold method with the write or writeln methods to format and display a string in a document. In server-side JavaScript, use the write function to display the string.

Examples
The following example uses string methods to change the formatting of a string:

var worldString="Hello, world"
document.write(worldString.blink())
document.write("<P>" + worldString.bold())
document.write("<P>" + worldString.italics())
document.write("<P>" + worldString.strike())

The previous example produces the same output as the following HTML:

<BLINK>Hello, world</BLINK>
<P><B>Hello, world</B>
<P><I>Hello, world</I>
<P><STRIKE>Hello, world</STRIKE>

See also
String.blink, String.italics, String.strike

charAt

Returns the specified character from the string.

Method of	String
Implemented in	JavaScript 1.0, NES 2.0
ECMA version	ECMA-262

Syntax
charAt(index)

Parameters

index

An integer between 0 and 1 less than the length of the string.

Description
Characters in a string are indexed from left to right. The index of the first character is 0, and the index of the last character in a string called stringName is stringName.length - 1. If the index you supply is out of range, JavaScript returns an empty string.

Examples
The following example displays characters at different locations in the string "Brave new world":

var anyString="Brave new world"

document.writeln("The character at index 0 is " + anyString.charAt(0))
document.writeln("The character at index 1 is " + anyString.charAt(1))
document.writeln("The character at index 2 is " + anyString.charAt(2))
document.writeln("The character at index 3 is " + anyString.charAt(3))
document.writeln("The character at index 4 is " + anyString.charAt(4))

These lines display the following:

The character at index 0 is B
The character at index 1 is r
The character at index 2 is a
The character at index 3 is v
The character at index 4 is e

See also
String.indexOf, String.lastIndexOf, String.split

charCodeAt

Returns a number indicating the Unicode value of the character at the given index.

Method of	String
Implemented in	JavaScript 1.2, NES 3.0 JavaScript 1.3: returns a Unicode value rather than an ISO-Latin-1 value.
ECMA version	ECMA-262

Syntax
charCodeAt([index])

Parameters

index

An integer between 0 and 1 less than the length of the string. The default value is 0.

Description
Unicode values range from 0 to 65,535. The first 128 Unicode values are a direct match of the ASCII character set. For information on Unicode, see the Core JavaScript Guide.

Backward Compatibility

JavaScript 1.2. The charCodeAt method returns a number indicating the ISO-Latin-1 codeset value of the character at the given index. The ISO-Latin-1 codeset ranges from 0 to 255. The first 0 to 127 are a direct match of the ASCII character set.

Example
The following example returns 65, the Unicode value for A.

"ABC".charCodeAt(0) // returns 65

concat

Combines the text of two or more strings and returns a new string.

Method of	String
Implemented in	JavaScript 1.2, NES 3.0

Syntax
concat(string2, string3[, ..., stringN])

Parameters

string2... stringN

Strings to concatenate to this string.

Description
concat combines the text from one or more strings and returns a new string. Changes to the text in one string do not affect the other string.

Example
The following example combines two strings into a new string.

s1="Oh "
s2="what a beautiful "
s3="mornin'."
s4=s1.concat(s2,s3) // returns "Oh what a beautiful mornin'."

constructor

Specifies the function that creates an object's prototype. Note that the value of this property is a reference to the function itself, not a string containing the function's name.

Property of	String
Implemented in	JavaScript 1.1, NES 2.0
ECMA version	ECMA-262

Description
See Object.constructor.

fixed

Causes a string to be displayed in fixed-pitch font as if it were in a TT tag.

Method of	String
Implemented in	JavaScript 1.0, NES 2.0

Syntax
fixed()

Parameters
None

Description
Use the fixed method with the write or writeln methods to format and display a string in a document. In server-side JavaScript, use the write function to display the string.

Examples
The following example uses the fixed method to change the formatting of a string:

var worldString="Hello, world"
document.write(worldString.fixed())

The previous example produces the same output as the following HTML:

<TT>Hello, world</TT>

fontcolor

Causes a string to be displayed in the specified color as if it were in a <FONT COLOR=color> tag.

Method of	String
Implemented in	JavaScript 1.0, NES 2.0

Syntax
fontcolor(color)

Parameters

color

A string expressing the color as a hexadecimal RGB triplet or as a string literal. String literals for color names are listed in the Core JavaScript Guide.

Description
Use the fontcolor method with the write or writeln methods to format and display a string in a document. In server-side JavaScript, use the write function to display the string.

If you express color as a hexadecimal RGB triplet, you must use the format rrggbb. For example, the hexadecimal RGB values for salmon are red=FA, green=80, and blue=72, so the RGB triplet for salmon is "FA8072".

The fontcolor method overrides a value set in the fgColor property.

Examples
The following example uses the fontcolor method to change the color of a string:

var worldString="Hello, world"

document.write(worldString.fontcolor("maroon") +
   " is maroon in this line")
document.write("<P>" + worldString.fontcolor("salmon") +
   " is salmon in this line")
document.write("<P>" + worldString.fontcolor("red") +
   " is red in this line")

document.write("<P>" + worldString.fontcolor("8000") +
   " is maroon in hexadecimal in this line")
document.write("<P>" + worldString.fontcolor("FA8072") +
   " is salmon in hexadecimal in this line")
document.write("<P>" + worldString.fontcolor("FF00") +
   " is red in hexadecimal in this line")

The previous example produces the same output as the following HTML:

<FONT COLOR="maroon">Hello, world</FONT> is maroon in this line
<P><FONT COLOR="salmon">Hello, world</FONT> is salmon in this line
<P><FONT COLOR="red">Hello, world</FONT> is red in this line

<FONT COLOR="8000">Hello, world</FONT>
is maroon in hexadecimal in this line
<P><FONT COLOR="FA8072">Hello, world</FONT>
is salmon in hexadecimal in this line
<P><FONT COLOR="FF00">Hello, world</FONT>
is red in hexadecimal in this line

fontsize

Causes a string to be displayed in the specified font size as if it were in a <FONT SIZE=size> tag.

Method of	String
Implemented in	JavaScript 1.0, NES 2.0

Syntax
fontsize(size)

Parameters

size	An integer between 1 and 7, a string representing a signed integer between 1 and 7.

Description
Use the fontsize method with the write or writeln methods to format and display a string in a document. In server-side JavaScript, use the write function to display the string.

When you specify size as an integer, you set the size of stringName to one of the 7 defined sizes. When you specify size as a string such as "-2", you adjust the font size of stringName relative to the size set in the BASEFONT tag.

Examples
The following example uses string methods to change the size of a string:

var worldString="Hello, world"

document.write(worldString.small())
document.write("<P>" + worldString.big())
document.write("<P>" + worldString.fontsize(7))

The previous example produces the same output as the following HTML:

<SMALL>Hello, world</SMALL>
<P><BIG>Hello, world</BIG>
<P><FONTSIZE=7>Hello, world</FONTSIZE>

See also
String.big, String.small

fromCharCode

Returns a string created by using the specified sequence of Unicode values.

Method of	String
Static
Implemented in	JavaScript 1.2, NES 3.0 JavaScript 1.3: uses a Unicode value rather than an ISO-Latin-1 value.
ECMA version	ECMA-262

Syntax
fromCharCode(num1, ..., numN)

Parameters

num1, ..., numN

A sequence of numbers that are Unicode values.

Description
This method returns a string and not a String object.

Because fromCharCode is a static method of String, you always use it as String.fromCharCode(), rather than as a method of a String object you created.

Backward Compatibility

JavaScript 1.2. The fromCharCode method returns a string created by using the specified sequence of ISO-Latin-1 codeset values.