STRING:
JavaScript will store any
text inside double quotes “” or single quotes ‘’.
Example: “My first Java
Program” or ‘My first Java Program’.
JavaScript String Methods:
indexOf()
The index of method will
return the first occurrence of a particular text in a string.
Example: var a = "My
name is Arun. My father's name is Ashok";
alert(a.indexOf('name'));
In the above example name
is appearing twice. But it will take the position of the first time
“name” and will return 3 .
Result: 3
lastIndexOf()
The index of method will
return the first occurrence of a particular text in a string.
Example: var a = "My
name is Arun. My father's name is Ashok";
alert(a.lastIndexOf('name'));
In the above example name
is appearing twice. But it will take the position of the last
position of “name” and will return 29 .
Result: 29
Both the indexOf(), and
the lastIndexOf() methods return -1 if the text is not found.
toUpperCase()
It will convert the string
in uppercase.
Example: var a = "Live
life to the fullest";
alert(a.toUpperCase());
Result: LIVE
LIFE TO THE FULLEST
toLowerCase()
It will convert the string
in uppercase.
Example: var a = "Live
life to the fullest";
alert(a.toLowerCase());
Result: live
life to the fullest
length
It will return length of
the string.
Example: var a =
"Live life to the fullest";
alert(a.length);
It will count
total letters in a string and blank spaces too and return total value
of
it.
Result: 24
charAt()
It will return character
for the given position.
Example: var a = "Live life to the fullest";
alert(a.charAt(2));
Result: v
For Invalid values:-
Example: var a = "Live life to the fullest";
alert(a.charAt(26));
Result: Null
substr()
Syntax: substr(Begin
Index, no. of values)
Begin index will take the
position of the character in a string and will display values
depending upon the index value and number given.
Example: var a =
"Live life to the fullest";
alert(a.substr(2,6));
Result: ve
lif
For Invalid values:-
Example: var a = "Live life to the fullest";
alert(a.substr(27,6));
Result: Nothing
substring()
Syntax: substr(Begin
Index, End Index)
Begin index will take the
position of the character in a string and will display values
depending upon the index value and number given.
Example: var a = "Live life to the fullest";
alert(a.substr(2,6));
Result: ve lif
Example: var a = "Live life to the fullest";
alert(a.substr(27,6));
Result: Nothing
Match()
It will match the value
given with the string and return it.
Example: var a = "Live
life to the fullest";
alert(a.match(‘l’));
Result: l
For Invalid values:-
Example: var a =
"Live life to the fullest";
alert(a.match(‘z’));
Result: Null
Replace()
It will replace a
specified value with the given value in the string.
Example: var a = "Live
life to the fullest";
alert(a.replace(‘l’ , ‘m’));
Result: Mive mife to the
fummest
Example: var a = "Live
life to the fullest";
alert(a.replace(‘o’ , ‘z’));
Result: Live life to the
fullest
It will return the string
as it is.
Search()
This method will search
the sting for the given value and returns the position of the value.
Example: var a = "Live
life to the fullest";
alert(a.search(‘l’));
Result: 5, not 0 because JavaScript is case sensitive. If we will search L, then it will
return 0.Also it will
include blank spaces while counting the position.
For Invalid values:-
Example: var a = "Live
life to the fullest";
alert(a.search(‘q’));
Result: -1
REGULAR EXPRESSION
Regular expression is used
to perform all types of text searches/replace operations on the basis
of given modifiers..
Syntax:
/pattern/modifiers;
Different Types of
Modifiers:
1. i : Using this modifier
will do case sensitive matching
2. g : It will do global
match which means it will find all the matches in a string rather
than stopping after first match.
3. m : It will do
multiline matching.
Example:
var str = 'admec
multimedia institute';
alert(str.search(/MULTIMEDIA/i));
Result: 6, As we have used
search method it will search for the given value and return the
position of the given value. Also as we have used ‘i’ as the
modifier it will do case sensitive matching.
Example:
var str = 'admec
multimedia institute';
var patt = /A/gi;
alert(str.replace(patt,
'z'));
Result: zdmec multimediz
institute, As we have used replace method and ‘g’ and ‘I’
modifier it will do case sensitive matching and replace all A with z.
Test() Method
It will search a string
for a pattern and will return true or false value depending upon the
search.
Example:
var str = 'admec
multimedia institute3';
var patt = /[0-9]/gi;
if(patt.test(str) ==
false)
alert('valid name
given');
else{
alert('invalid name
given');
}
Result:
invalid name given, it will search for values between[0-9]. If it’s
there in the string it will execute the else statement and will
print ‘invalid name given’.
