String
constructor:
new String(string);
string | Any string. |
Description
The String
object is a built-in JavaScript object. You an treat any JavaScript string as a String
object.
A string can be represented as a literal enclosed by single or double quotation marks; for example, "Netscape" or 'Netscape'.
Property Summary
| Reflects the length of the string. |
|
Allows the addition of properties to a String object.
|
Examples
Example 1: String variable. The following statement creates a string variable:
var last_name = "Schaefer"
Example 2: String object properties. The following statements evaluate to 8, "SCHAEFER,"
and "schaefer"
:
last_name.length
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:
last_name.toUpperCase()
last_name.toLowerCase()var myString = "Hello"
displays "The first character in the string is H"
"The first character in the string is " + myString[0] Properties
length
The length of the string.
Property of |
String
|
Read-only |
Description
For a null string, length is 0.
Examples
The following example displays "The string length is 8":
var x="Netscape"
"The string length is " + x.lengthprototype
Represents the prototype for this class. You can use the prototype to add properties or methods to all instances of a class. For information on prototypes, see Function.prototype
.
Property of |
String
|
Methods
anchor
Creates an HTML A tag.
Method of |
String
|
Syntax
anchor(nameAttribute)
Parameters
nameAttribute | A string. |
Description
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.
Examples
The following example creates an anchor for the table of contents:
var myString="Table of Contents"
The previous example produces the following output:
myString.anchor("contents_anchor")<A NAME="contents_anchor">Table of Contents</A>
See also
String.link
Method of |
String
|
Syntax
big()
Parameters
None
Examples
var worldString="Hello, world"
worldString.big()
The previous example produces the following outputs:
<BIG>Hello, world</BIG>
See also
String.fontsize
, String.small
blink
Creates an HTML BLINK tag.
Method of |
String
|
Syntax
blink()
Parameters
None
Examples
var worldString="Hello, world"
worldString.blink()
The previous example produces the following output:
<BLINK>Hello, world</BLINK>
See also
String.bold
, String.italics
, String.strike
Method of |
String
|
Syntax
bold()
Parameters
None
Examples
var worldString="Hello, world"
The previous example produces the following output:
worldString.bold()<B>Hello, world</B>
See also
String.blink
, String.italics
, String.strike
charAt
Returns the specified character from the string.
Method of |
String
|
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"
"The character at index 0 is " + anyString.charAt(0)
These lines display the following:
The character at index 0 is B
"The character at index 1 is " + anyString.charAt(1)
"The character at index 2 is " + anyString.charAt(2)
"The character at index 3 is " + anyString.charAt(3)
"The character at index 4 is " + anyString.charAt(4)
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 ISO-Latin-1 codeset value of the character at the given index.
Method of |
String
|
Syntax
charCodeAt(index)
Parameters
index | (Optional) An integer between 0 and 1 less than the length of the string. The default value is 0. |
Description
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 ISO-Latin-1 codeset value for A.
"ABC".charCodeAt(0)
concat
Combines the text of two strings and returns a new string.
Method of |
String
|
Syntax
concat(string2)
Parameters
string1 | The first string. |
string2 | The second string. |
Description
concat
combines the text from two 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.
This writes:
The morning is upon us.
str1="The morning is upon us. "
str2="The sun is bright."
str3=str1.concat(str2)
The sun is bright.
The morning is upon us. The sun is bright.
fixed
Creates an HTML TT tag.
Method of |
String
|
Syntax
fixed()
Parameters
None
Examples
var worldString="Hello, world"
The previous example produces the following output:
worldString.fixed()<TT>Hello, world</TT>
fontcolor
Creates an HTML FONT COLOR tag.
Method of |
String
|
Syntax
fontcolor(color)
Parameters
color | A string expressing the color as a hexadecimal RGB triplet or as a string literal. |
Description
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"
.
Examples
var worldString="Hello, world"
worldString.fontcolor("maroon")
worldString.fontcolor("FA8072")
The previous examples produce the following output:
<FONT COLOR="maroon">Hello, world</FONT>
<FONT COLOR="FA8072">Hello, world</FONT>
fontsize
Creates an HTML FONT SIZE tag.
Method of |
String
|
Syntax
fontsize(size)
Parameters
size | An integer between 1 and 7, a string representing a signed integer between 1 and 7. |
Description
Examples
var worldString="Hello, world"
worldString.fontsize(7)
The previous example produces the following output:
<FONTSIZE=7>Hello, world</FONTSIZE>
See also
String.big
, String.small
fromCharCode
Returns a string created by using the specified sequence ISO-Latin-1 codeset values.
Method of |
String
|
Static |
Syntax
fromCharCode(num1, ..., numN)
Parameters
num1, ..., numN | A sequence of numbers that are ISO-Latin-1 codeset 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.
Example
The following example returns the string "ABC".
String.fromCharCode(65,66,67)
indexOf
Returns the index within the calling String
object of the first occurrence of the specified value, starting the search at fromIndex
, or -1 if the value is not found.
Method of |
String
|
Syntax
indexOf(searchValue, fromIndex)
Parameters
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 of a string called stringName
is stringName.length - 1
.
If stringName
contains an empty string (""
), indexOf
returns an empty string.
The indexOf
method is case sensitive. For example, the following expression returns -1:
"Blue Whale".indexOf("blue")
Examples
Example 1. The following example uses indexOf
and lastIndexOf
to locate values in the string "Brave new world."
var anyString="Brave new world"
//Displays 8
Example 2. The following example defines two string variables. The variables contain the same string except that the second string contains uppercase letters. The first
"The index of the first w from the beginning is " +
anyString.indexOf("w")
//Displays 10
"The index of the first w from the end is " +
anyString.lastIndexOf("w")
//Displays 6
"The index of 'new' from the beginning is " +
anyString.indexOf("new")
//Displays 6
"The index of 'new' from the end is " +
anyString.lastIndexOf("new")indexOf
call returns 19. But because the indexOf
method is case sensitive, the string "cheddar"
is not found in myCapString
, so the second indexOf
call returns -1.
myString="brie, pepper jack, cheddar"
Example 3. The following example sets
myCapString="Brie, Pepper Jack, Cheddar"
'myString.indexOf("cheddar") is ' +
myString.indexOf("cheddar")
'myCapString.indexOf("cheddar") is ' +
myCapString.indexOf("cheddar")count
to the number of occurrences of the letter x
in the string str
:
count = 0;
pos = str.indexOf("x");
while ( pos != -1 ) {
count++;
pos = str.indexOf("x",pos+1);
} See also
String.charAt
, String.lastIndexOf
, String.split
italics
Creates an HTML I tag.
Method of |
String
|
Syntax
italics()
Parameters
None
Examples
var worldString="Hello, world"
worldString.italics()
The previous example produces the following output:
<I>Hello, world</I>
See also
String.blink
, String.bold
, String.strike
lastIndexOf
Returns the index within the calling String
object of the last occurrence of the specified value. The calling string is searched backward, starting at fromIndex
, or -1 if not found.
Method of |
String
|
Syntax
lastIndexOf(searchValue, fromIndex)
Parameters
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 is stringName
.length - 1.
The lastIndexOf
method is case sensitive. For example, the following expression returns -1:
"Blue Whale, Killer Whale".lastIndexOf("blue")
Examples
The following example uses indexOf
and lastIndexOf
to locate values in the string "Brave new world."
var anyString="Brave new world"
//Displays 8
"The index of the first w from the beginning is " +
anyString.indexOf("w")
//Displays 10
"The index of the first w from the end is " +
anyString.lastIndexOf("w")
//Displays 6
"The index of 'new' from the beginning is " +
anyString.indexOf("new")
//Displays 6
"The index of 'new' from the end is " +
anyString.lastIndexOf("new") See also
String.charAt
, String.indexOf
, String.split
link
Creates an HTML A HREF tag.
Method of |
String
|
Syntax
link(hrefAttribute)
Examples
The following example displays the word "Netscape" as a hypertext link that points to the Netscape home page:
var hotText="Netscape"
var URL="http://home.netscape.com"hotText.link(URL)
The previous example produces the following output:
<A HREF="http://home.netscape.com">Netscape</A>
See also
Anchor
match
Used to match a regular expression against a string.
Method of |
String
|
Syntax
match(regexp)
Parameters
regexp | Name of the regular expression. It can be a variable name or a literal. |
Description
If you want to execute a global match, or a case insensitive match, include the g
(for global) and i
(for ignore case) flags in the regular expression. These can be included separately or together. The following two examples below show how to use these flags with match
.
Note
If you execute a match simply to find true or false, use String.search
or the regular expression test
method.
Examples
Example 1. In the following example, match
is used to find 'Chapter' followed by 1 or more numeric characters followed by a decimal point and numeric character 0 or more times. The regular expression includes the i
flag so that case will be ignored.
str = "For more information, see Chapter 3.4.5.1";
This returns the array containing Chapter 3.4.5.1,Chapter 3.4.5.1,.1
re = /(chapter \d+(\.\d)*)/i;
found = str.match(re);'Chapter 3.4.5.1'
is the first match and the first value remembered from (Chapter \d+(\.\d)*)
.
'.1'
is the second value remembered from (\.\d)
.
Example 2. The following example demonstrates the use of the global and ignore case flags with match
.
str = "abcDdcba";
The returned array contains D, d.
newArray = str.match(/d/gi);replace
Used to find a match between a regular expression and a string, and to replace the matched substring with a new substring.
Method of |
String
|
Syntax
replace(regexp, newSubStr)
Parameters
Description
This method does not change the String
object it is called on; it simply returns a new string.
If you want to execute a global search and replace, or a case insensitive search, include the g
(for global) and i
(for ignore case) flags in the regular expression. These can be included separately or together. The following two examples below show how to use these flags with replace
.
Examples
Example 1. In the following example, the regular expression includes the global and ignore case flags which permits replace
to replace each occurrence of 'apples' in the string with 'oranges.'
re = /apples/gi;
This prints "oranges are round, and oranges are juicy."
Example 2. In the following example, the regular expression is defined in
str = "Apples are round, and apples are juicy.";
newstr=str.replace(re, "oranges");replace
and includes the ignore case flag.
str = "Twas the night before Xmas...";
This prints "Twas the night before Christmas..."
Example 3. The following script switches the words in the string. For the replacement text, the script uses the values of the
newstr=str.replace(/xmas/i, "Christmas");$1
and $2
properties.
re = /(\w+)\s(\w+)/;
This prints "Smith, John".
str = "John Smith";
newstr = str.replace(re, "$2, $1");search
Executes the search for a match between a regular expression and this String
object.
Method of |
String
|
Syntax
search(regexp)
Parameters
regexp | Name of the regular expression. It can be a variable name or a literal. |
Description
If successful, search
returns the index of the regular expression inside the string. Otherwise, it returns -1.
When you want to know whether a pattern is found in a string use search
(similar to the regular expression test
method); for more information (but slower execution) use match
(similar to the regular expression exec
method).
Example
The following example prints a message which depends on the success of the test.
function testinput(re, str){
if (str.search(re) != -1)
midstring = " contains ";
else
midstring = " does not contain ";
print (str + midstring + re.source);
}slice
Extracts a section of a string and returns a new string.
Method of |
String
|
Syntax
slice(beginslice,endSlice)
Parameters
beginSlice | The zero-based index at which to begin extraction. |
endSlice |
(Optional) The zero-based index at which to end extraction. If omitted, slice extracts to the end of the string.
|
Description
slice
extracts the text from one string and returns a new string. Changes to the text in one string do not affect the other string.
slice
extracts up to but not including endSlice
. string.slice(1,4)
extracts the second character through the fourth character (characters indexed 1, 2, and 3).
As a negative index, endSlice
indicates an offset from the end of the string. string.slice(2,-1)
extracts the third character through the second to last character in the string.
Example
The following example uses slice
to create a new string.
str1="The morning is upon us. "
This writes:
morning is upon
str2=str1.slice(3,-5)small
Creates an HTML SMALL tag.
Method of |
String
|
Syntax
small()
Parameters
None
Examples
var worldString="Hello, world"
worldString.small()
The previous example produces the following output:
<SMALL>Hello, world</SMALL>
See also
String.big
, String.fontsize
split
Splits a String
object into an array of strings by separating the string into substrings.
Method of |
String
|
Syntax
split(separator, limit)
Parameters
Description
The split
method returns the new array.
When found, separator
is removed from the string and the substrings are returned in an array. If separator
is omitted, the array contains one element consisting of the entire string.
Split
has the following additions:
function splitString (stringToSplit,separator) {
arrayOfStrings = stringToSplit.split(separator)
print ('The original string is: "' + stringToSplit + '"')
print ('The separator is: "' + separator + '"')
print ("The array has " + arrayOfStrings.length + " elements: ")
for (var i=0; i < arrayOfStrings.length; i++) {
print (arrayOfStrings[i] + " / ")
}
}
var tempestString="Oh brave new world that has such people in it."
var monthString="Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec"
var space=" "
var comma=","
splitString(tempestString,space)This example produces the following output:
splitString(tempestString)
splitString(monthString,comma)
The original string is: "Oh brave new world that has such people in it."
The separator is: " "
The array has 10 elements: Oh / brave / new / world / that / has / such / people / in / it. /
The original string is: "Oh brave new world that has such people in it."
The separator is: "undefined"
The array has 1 elements: Oh brave new world that has such people in it. /
The original string is: "Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec"Example 2. Consider the following script:
The separator is: ","
The array has 12 elements: Jan / Feb / Mar / Apr / May / Jun / Jul / Aug / Sep / Oct / Nov / Dec /
version(120)Using
str="She sells seashells \nby the\n seashore"
str.split(" ")
version(120)
, this script produces
"She", "sells", "seashells", "by", "the", "seashore"Without
version(120)
, this script splits only on single space characters, producing
"She", "sells", , , , "seashells", "by", , , "the", "seashore"Example 3. In the following example,
split
looks for 0 or more spaces followed by a semicolon followed by 0 or more spaces and, when found, removes the spaces from the string. nameList
is the array returned as a result of split
.
names = "Harry Trump ;Fred Barney; Helen Rigby ; Bill Abel ;Chris Hand ";
re = /\s*;\s*/;
nameList = names.split (re);
nameList
contains the resulting array.
Harry Trump,Fred Barney,Helen Rigby,Bill Abel,Chris Hand
Example 4. In the following example, split
looks for 0 or more spaces in a string and returns the first 3 splits that it finds.
version(120)This script displays the following:
myVar = " Hello World. How are you doing? ";
myVar.split(" ", 3);
["Hello", "World.", "How"]
String.charAt
, String.indexOf
, String.lastIndexOf
strike
Creates an HTML STRIKE tag.
Method of |
String
|
Syntax
strike()
Parameters
None
Examples
The following example uses string
methods to change the formatting of a string:
var worldString="Hello, world"
worldString.strike()
The previous example produces the following output:
<STRIKE>Hello, world</STRIKE>
See also
String.blink
, String.bold
, String.italics
Method of |
String
|
Syntax
sub()
Parameters
None
Examples
The following example uses the sub
and sup
methods to format a string:
var subText="subscript"
"This is what a " + subText.sub() + " looks like."
The previous example produces the following output:
This is what a <SUB>subscript</SUB> looks like.
See also
String.sup
substr
Returns the characters in a string beginning at the specified location through the specified number of characters.
Method of |
String
|
Syntax
substr(start, length)
Parameters
start | Location at which to begin extracting characters. |
length | (Optional) The number of characters to extract |
Description
start
is a character index. The index of the first character is 0, and the index of the last character is 1 less than the length of the string. substr
begins extracting characters at start
and collects length
number of characters.
If start
is positive and is the length of the string or longer, substr
returns no characters.
If start
is negative, substr
uses it as a character index from the end of the string. If start
is negative and abs(start)
is larger than the length of the string, substr
uses 0 is the start index.
If length
is 0 or negative, substr
returns no characters. If length
is omitted, start
extracts characters to the end of the string.
Example
Consider the following script:
str = "abcdefghij"
This script displays:
"(1,2): ", str.substr(1,2)
"(-2,2): ", str.substr(-2,2)
"(1): ", str.substr(1)
"(-20, 2): ", str.substr(1,20)
"(20, 2): ", str.substr(20,2)(1,2): bc
(-2,2): ij
(1): bcdefghij
(-20, 2): bcdefghij
(20, 2): See also
substring
substring
Returns a subset of a String
object.
Method of |
String
|
Syntax
substring(indexA, indexB)
Parameters
indexA | An integer between 0 and 1 less than the length of the string. |
indexB | An integer between 0 and 1 less than the length of the string. |
Description
substring
extracts characters from indexA
up to but not including indexB
. In particular:
indexA
is less than 0, indexA
is treated as if it were 0.
indexB
is greater than stringName.length
, indexB
is treated as if it were stringName.length
.
indexA
equals indexB
, substring
returns an empty string.
indexB
is omitted, indexA
extracts characters to the end of the string.
substring
to display characters from the string "Netscape"
:
var anyString="Netscape"
//Displays "Net"Example 2. The following example replaces a substring within a string. It will replace both individual characters and substrings. The function call at the end of the example changes the string
anyString.substring(0,3)
anyString.substring(3,0)
//Displays "cap"
anyString.substring(4,7)
anyString.substring(7,4)
//Displays "Netscap"
anyString.substring(0,7)
//Displays "Netscape"
anyString.substring(0,8)
anyString.substring(0,10)
"Brave New World"
into "Brave New Web"
.
function replaceString(oldS,newS,fullS) {
// Replaces oldS with newS in the string fullS
for (var i=0; i<fullS.length; i++) {
if (fullS.substring(i,i+oldS.length) == oldS) {
fullS = fullS.substring(0,i)+newS+fullS.substring(i+oldS.length,fullS.length)
}
}
return fullS
}
replaceString("World","Web","Brave New World")
substr
Method of |
String
|
Syntax
sup()
Parameters
None
Examples
var superText="superscript"
"This is what a " + superText.sup() + " looks like."
The previous example produces the following output:
This is what a <SUP>superscript</SUP> looks like.
See also
String.sub
toLowerCase
Returns the calling string value converted to lowercase.
Method of |
String
|
Syntax
toLowerCase()
Parameters
None
Description
The toLowerCase
method returns the value of the string converted to lowercase. toLowerCase
does not affect the value of the string itself.
Examples
The following example displays the lowercase string "alphabet"
:
var upperText="ALPHABET"
upperText.toLowerCase() See also
String.toUpperCase
toUpperCase
Returns the calling string value converted to uppercase.
Method of |
String
|
Syntax
toUpperCase()
Parameters
None
Description
The toUpperCase
method returns the value of the string converted to uppercase. toUpperCase
does not affect the value of the string itself.
Examples
The following example displays the string "ALPHABET"
:
var lowerText="alphabet"
lowerText.toUpperCase() See also
String.toLowerCase
Last Updated: 10/31/97 12:30:31