String Manipulation Functions

String variables in JavaScript have a number of very useful string functions. Here's a sample of the most commonly used:  

Operation / Function

Example

Concatenation (+)

var S1 = "Customer";
var S2 = "123456"; 
var S3 = S1 + " " + S2 + "could not be found";

 

puts Customer 123456could not be found in variable S3. 

IndexOf – finds first occurrence of a string in a string

/*        012345678901 */
var S1 = "ABCDHELLOABC";
var pos = S1.indexOf("HELLO");

 

will put the number 4 into variable pos.  

lastIndexOf - finds last occurrence of a string in a string

/*        012345678901 */
var S1 = "ABCDHELLOABC";
var pos = S1.lastIndexOf("AB");

 

will put the number 9 into variable pos.  

charAt – returns the character at a specific position in a string

/*        012345678901 */
var S1 = "ABCDHELLOABC";
var S2 = S1.charAt(4);
var S3 = S1.charAt(9);

 

will put "H" into S2 and "A" into S3.

length – returns the length of a string

/*        012345678901  */
var S1 = "ABCDHELLOABC";
var I  = S1.length;

 

will put the number 11 into variable I.

substring – returns the substring of string using a starting and ending point.

/*       01234567789  */
var a = "Hello World";
var b = a.substring(4,8);

 

will put "o Wor" into b.

 

substr – returns the substring of a string using a starting position and a length

/*       01234567789  */
var a = "Hello World";
var b = a.substr(2,3);

 

will put "llo" into b.

 

toLowerCase – returns the lowercase of string

var a = "Hello World";
var b = a.toLowerCase();

 

will put "hello world" into b.

 

toUpperCase – returns the uppercase of a string

var a = "Hello World";
var b = a.toUpperCase();

 

will put "HELL WORLD" into b.

 

 

There are more string functions like these available. See:

http://www.w3schools.com/jsref/jsref_obj_string.asp for more details.