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[Previous] [Next] [Last]This section describes the new methods for strings. * indicates a change to an existing method.
charCodeAt--returns
a number indicating the ISO-Latin-1 codeset value of the character at the given index.
concat--combines
the text of two strings and returns a new string.
fromCharCode--constructs
a string from the specified sequence of numbers that are ISO-Latin-1 codeset values.
match--used
to match a regular expression against a string
replace--used
to find a match in a string, and replace the matched substring with a replacement
substring.
search--used
to test for a match in a string.
slice--extracts
a section of an string and returns a new string.
split*--uses
a regular expression or a fixed string as its argument to split a string.
substr--returns
the characters in a string collecting the specified number of characters beginning with a
specified location in the string.
substring*--When
the <SCRIPT> tag includes LANGUAGE="JavaScript1.2",
substring(x,y) no longer swaps x and y.
Core method. Returns a number indicating the ISO-Latin-1 codeset value of the character at the given index.
string.charCodeAt([index])
string
is any string.
index, an optional argument, is any integer from 0
to string.length-1, or a property of an existing object. The default value is
0.
String
object
The ISO-Latin-1 codeset ranges from 0 to 255. The first 0 to 127 are a direct match of the ASCII character set.
The following example returns the ISO-Latin-1 codeset value of 65.
"ABC".charCodeAt(0)
Core method. Combines the text of two strings and returns a new string.
string1.concat(string2)
string1
is the first string.
string2 is the second string.
String
object
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.
The following example combines two strings into a new string.
<SCRIPT LANGUAGE="JavaScript1.2"> str1="The morning is upon us. " str2="The sun is bright." str3=str1.concat(str2) document.write(str3) </SCRIPT>
This writes:
The morning is upon us. The sun is bright.Core method. Returns a string from the specified sequence of numbers that are ISO-Latin-1 codeset values.
String.fromCharCode(num1, num2, ..., numn)
numn
is a sequence of numbers that are ISO-Latin-1 codeset values.
String
object
This method returns a string and not a String object.
Example 1.:
The following example returns the string "ABC".String.fromCharCode(65,66,67)
Example 2. :
Thewhich property of the KeyDown,
KeyPress, and KeyUp events contains the ASCII value of the key pressed at the time the
event occurred. If you want to get the actual letter, number, or symbol of the key, you
can use fromCharCode. The following example returns the letter, number, or
symbol of the KeyPress event's which property.
String.fromCharCode(KeyPress.which)
Core method. Used to match a regular expression against a string.
string.match(regexp)
string
is any string.
regexp is the name of the regular expression. It can
be a variable name or a literal.
String
object
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.
Example 1.:
In the following example,match is
used to find 'Chapter' followed by one or more numeric characters followed by
a decimal point and numeric character zero or more times. The regular expression includes
the i flag so that case will be ignored.
<SCRIPT LANGUAGE="JavaScript1.2"> str = "For more information, see Chapter 3.4.5.1"; re = /(chapter \d+(\.\d)*)/i; found = str.match(re); document.write(found); </SCRIPT >
This returns the array containing
Chapter 3.4.5.1,Chapter 3.4.5.1,.1
'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.
<SCRIPT LANGUAGE="JavaScript1.2"> str = "abcDdcba"; newArray = str.match(/d/gi); document.write(newArray); </SCRIPT >
The returned array contains D, d.
Core method. Used to find a match between a regular expression and a string, and to replace the matched substring with a new substring.
string.replace(regexp, newSubStr)
string
is a string. This string can include the RegExp properties $1,...,
$9, lastMatch, lastParen, leftContext,
and rightContext.
regexp is the name of the regular expression. It can
be a variable name or a literal.
newSubStr is the string to replace the string found
with regexp.
String
object
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.
Example 1. :
In the following example, the regular expression includes the global and ignore case flags which permitsreplace to replace
each occurrence of 'apples' in the string with 'oranges.'
<SCRIPT LANGUAGE="JavaScript1.2"> re = /apples/gi; str = "Apples are round, and apples are juicy."; newstr=str.replace(re, "oranges"); document.write(newstr) </SCRIPT>
This prints "oranges are round, and oranges are juicy."
Example 2.: In the following example, the regular expression is defined inreplace
and includes the ignore case flag.
<SCRIPT LANGUAGE="JavaScript1.2"> str = "Twas the night before Xmas..."; newstr=str.replace(/xmas/i, "Christmas"); document.write(newstr) </SCRIPT>
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$1 and $2 properties.
<SCRIPT LANGUAGE="JavaScript1.2"> re = /(\w+)\s(\w+)/; str = "John Smith"; newstr = str.replace(re, "$2, $1"); document.write(newstr) </SCRIPT>
This prints "Smith, John".
Core method. Executes the search for a match between a regular expression and a specified string.
string.search(regexp)
string
is any string.
regexp is the name of the regular expression. It can
be a variable name or a literal.
If successful, search returns the index of the regular expression inside
the string. Otherwise, it returns -1.
search
(similar to the regular expression test method); for more information (but
slower execution) use match (similar to the regular expression exec
method).
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 ";
document.write (str + midstring + re.source);
}
Core method. Extracts a section of an string and returns a new string.
string.slice(beginslice,[endSlice])
string
is a string.
beginSlice is the zero-based index at which to begin
extraction.
endSlice is the zero-based index at which to end
extraction.
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) 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. endSlice is omitted, slice extracts to the end of the
string.
String
object
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.
The following example uses slice to create a new string.
<SCRIPT LANGUAGE="JavaScript1.2"> str1="The morning is upon us. " str2=str1.slice(3,-5) document.write(str2) </SCRIPT>
This writes:
morning is uponCore method. split has the following additions:
LANGUAGE="JavaScript1.2" in the <SCRIPT>
tag, string.split(" ") splits on any run of one or more white
space characters including spaces, tabs, line feeds, and carriage returns. string.split([separator], [limit])
string
is any string.
separator specifies the character or regular
expression to use for separating the string.
limit is an optional integer that specifies a limit
on the number of splits to be found.
String
object
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.
separator is a regular expression, any included
parenthesis cause submatches to be included in the returned array.
Using the optional limit argument, you can avoid including
trailing empty elements in the returned array.
Example 1.:
UsingLANGUAGE="JavaScript1.2",
the following script produces
["She", "sells", "seashells", "by", "the", "seashore"]
<SCRIPT LANGUAGE="JavaScript1.2">
str="She sells seashells \nby the\n seashore"
document.write(str + "<BR>")
a=str.split(" ")
document.write(a)
</SCRIPT>
Without LANGUAGE="JavaScript1.2", the above script splits only
on single space characters, producing
She,sells,,,,seashells, by,,,the ,seashore
Example 2.:
In the following example,split
looks for zero to many spaces followed by a semi-colon followed by zero to many spaces
and, when found, removes them from the string. nameList is the array returned
as a result of split.
<SCRIPT LANGUAGE="JavaScript1.2"> names = "Harry Trump ;Fred Barney; Helen Rigby ; Bill Abel ;Chris Hand "; document.write (names + "<BR>" + "<BR>"); re = /\s*;\s*/; nameList = names.split (re); document.write(nameList); </SCRIPT>
This prints two lines; the first line prints the original string, and the second line prints the resulting array.
Harry Trump ;Fred Barney; Helen Rigby ; Bill Abel ;Chris Hand ["Harry Trump", "Fred Barney", "Helen Rigby", "Bill Abel", "Chris Hand"]Core method. Returns the characters in a string beginning at the specified location through the specified number of characters.
str.substr(start, [length])
str
is any string.
start is the location at which to begin extracting
characters.
length, an optional argument, is the number of
characters to extract.
String
object
start
is a character index. The index of the first character is 0, and the index
of the last character is str.length-1. substr begins extracting
characters at start and collects length number of characters.
If start is positive and is longer than str.length-1,
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.
Consider the following script:
<SCRIPT LANGUAGE="JavaScript1.2">
str = "abcdefghij"
document.writeln("(1,2): ", str.substr(1,2))
document.writeln("(-2,2): ", str.substr(-2,2))
document.writeln("(1): ", str.substr(1))
document.writeln("(-20, 2): ", str.substr(1,20))
document.writeln("(20, 2): ", str.substr(20,2))
</SCRIPT>
This script displays:
(1,2): bc (-2,2): ij (1): bcdefghij (-20, 2): bcdefghij (20, 2):
If you specify LANGUAGE="JavaScript1.2" in the script tag, substring(x,y)
no longer swaps x and y.
string.substring(indexA, [indexB])
string
is any string.
indexA is any integer from zero to stringName.length-1.
indexB, an optional argument, is any integer from
zero to stringName.length.
String
object
substring
behaves as follows:
indexA up to but not including indexB.
indexA is less than zero, 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. Using LANGUAGE="JavaScript1.2" in the <SCRIPT>
tag,
indexA is greater than indexB, JavaScript produces a
runtime error (out of memory). Without LANGUAGE="JavaScript1.2",
indexA is greater than indexB, JavaScript returns a
substring beginning with indexB and ending with indexA-1. Using LANGUAGE="JavaScript1.2", the following script produces a
runtime error (out of memory).
<SCRIPT LANGUAGE="JavaScript1.2"> str="Netscape" document.write(str.substring(0,3); document.write(str.substring(3,0); </SCRIPT>
Without LANGUAGE="JavaScript1.2", the above script prints
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