var strnew="Hello Raghu How are u"

Checking existence in entire string
====================================

if(strnew.indexOf("Raghu") != -1 )
{
    alert("Exists");
}

Checking existence at the end of string
===============================================
For example, variable result1 in the following example is assigned 
the value of true because the word "Ishmael" appears at the end of 
the string. Variable result2 is assigned a value of false because 
"Raghu" doesn't appear at the end of the string.
---------------------------------------------------------------------

result1 = /Raghu$/.test("Call me Raghu");
result2 = /Raghu$/.test("Call me Raghu. Some years ago"); 

Checking existence in the begining of string
=====================================================
In the following example, variable result1 is assigned the value 
of true because the word "Birds" appears at the beginning of the 
string. Variable result2 is assigned the value of false because 
"Birds" doesn't appear at the beginning of the string.
-------------------------------------------------------------------

result1 = /^Birds/.test("Birds fly");
result2 = /^Birds/.test("Big Birds fly"); 
//javascript/166