What
is String?
String is a collection of characters.
Commonly used method of string object
are concatenating two strings, converting
the string to upper case or
lower case, finding the substring of
a given string.
String written
within the single or double quotes.
Manipulating
a String:
·
Manipulating string values is a common
developer chore. This ranges from
extracting portions of a string to determining if a string contains a
specific character. The following JavaScript functions provide developers with everything they need:
1.
concat() - Combines
the text of two or more strings
and returns a new string.
2.
indexOf() – Returns the
starting index of a substring within another string.
A –1 is returned if no match is found.
3.
charAt() – Returns
the character at the specified location.
4.
lastIndexOf() - Returns the index within
the string of the last
occurrence of the specified value, or -1 if not found.
5.
match() - Used to match a regular
expression against a string.
6.
substring() – A portion
of a string is returned. A starting and ending location are passed to this function.
7.
replace() – Used to find a match between
a regular expression and a string,
andto replace the matched substring
with a new substring.
8.
search() - Executes the
search for a match of a regular
expression. If successful, search returns the index of the match inside
the string. Otherwise, it returns -1.
9.
slice() - Extracts
a section of a string
and returns a new string.
10. split() - Splits a string into an array of strings
by separating the string intosubstrings.
11.
length() – The length
of the string is returned
as the count
of the number of
characters it contains.
12. toLowerCase() – Converts the entire string
to lowercase.
13. toUpperCase() – Converts the entire string
to uppercase.
Joining A String:
This method
adds two or more strings
and returns a new single
string. Syntax: string.concat(string2, string3[,
..., stringN]);
string2...stringN − These are the strings to be concatenated.
Retrieving
A Character From Given Position:
charAt() is a method that returns the character from the specified index.
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.
Syntax: string.charAt(index);
index − An integer between
0 and 1 less than the length
of the string.
Retrieving A Position Of Character In A String:
JavaScript array
indexOf() method returns
the first index
at which a given element can be found in the array,
or -1 if it is not present.
Syntax: string. indexOf(string); Dividing Text:
This method splits a String object
into an array
of strings by
separating the string into substrings.
Syntax: string.split([separator][, limit]);
separator − Specifies the character to use for
separating the string.
If separator is omitted, the
array returned contains one element consisting of the entirestring.
limit − Integer
specifying a limit on the number of splits to be found.
Copying
a Substring (Using of substr):
This method
returns the characters in a string
beginning at the specified location through the specified number of characters.
Syntax: string.substr(start[, length]);
start − Location at which to start extracting characters (an integer
between 0 and one
less than the length of the string).
length − The number of characters to extract.
Copying
a Substring (Using of substring):
This method returns a subset of a String
object. Syntax: string.substring(indexA, [indexB])
indexA − An integer between
0 and one less than the length of the string.
indexB − (optional)
An integer between 0 and the length of the string.
Converting
String To Number:
Converting string
to number we have different types of function
based on type
of numbers i.e. string
is to be converted to integer by using parseInt( ) method.
If string
is to be converted to float value then the method parseFloat().
Converting
Number To String:
This method
returns a string
representing the specified object. Syntax: string.toString( )
Returns a string representing the specified object.
Changing The Case Of String:
This method returns the calling string value converted to lowercase. Syntax:
string.toLowerCase( )
This method returns the calling string value converted to uppercase. Syntax:
string.toUpperCase( )
Conclusion: We understand that how to implement string using various
functions JavaScript.
JavaScript to
implement string.
A]
<html>
<body>
<script>
function func()
{
var s = 'It';
var value = s.concat(' is',' a',' great',' day.'); document.write("String after concat:
"+value);
var str = new String( "MVP RSM Polytechnic Nashik."); document.writeln("<br />String after
str.charAt(4) is: " + str.charAt(4)); document.writeln("<br
/>String after str.charAt(5) is: " + str.charAt(5)); var index =
str.indexOf( "Knowledge" );
document.write("<br />String after
indexOf : "
+ index ); var splitted = str.split("
", 2);
document.write( "<br />String after split : " +
splitted ); document.write("<br />String after substr : " +
str.substr(0,21)); document.write("<br
/>String after substring: " + str.substring(0, 20)); document.write("<br
/>String after toLowerCase: "+str.toLowerCase( ));
document.write("<br />String after toUpperCase:
"+str.toUpperCase( ));
}
func();
</script>
</body>
</html>
Output:
String after concat:
It is a great day. String after str.charAt(4) is: B
String after str.charAt(5) is: h String after indexOf : 12
B]
<html>
<body>
<script>
function func(){
var s ='Kya,';
var value = s.concat(' Baat', ' Hai'); document.write("String after concat: " + value);
var str = new String("Kudi kehndi pehle jaguar lelo."); document.writeln("<br />String after
str.charAt(4) is: " + str.charAt(4)); document.writeln("<br
/>String after str.charAt(5) is: " + str.charAt(5)); var index =
str.indexOf("Knowledge");
document.write("<br />String
after indexOf : " + index); var splitted =
str.split(" ", 2);
document.write("<br />String after split : " +
splitted); document.write("<br />String after substr : " +
str.substr(0, 21)); document.write("<br />String after substring: " + str.substring(0, 20)); document.write("<br
/>String after toLowerCase: " + str.toLowerCase());
document.write("<br />String after toUpperCase: " + str.toUpperCase());
}
func();
</script>
</body>
</html>
Output:
String after
concat: Kya, Baat
Hai String after str.charAt(4) is: String after str.charAt(5) is: k
String after indexOf : -1
String
after split : Kudi,kehndi String after substr
: Kudi kehndi pehle jag
String after substring: Kudi kehndi
pehle ja
String after
toLowerCase: kudi kehndi
pehle jaguar lelo.
String after toUpperCase: KUDI KEHNDI PEHLE JAGUAR LELO.
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