JavaScript: String Manipulation Functions

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.