Javascript functions can be declared on a objects prototype like this:

<object name>.prototype.<variable name>=function(){
//
//
}

How it this different than following declaration?

<object name>.<variable name>=function(){
//
//
}

How are prototype functions different than normal functions in javascript ?

Javascript functions can be declared on a objects prototype like this:

<object name>.prototype.<variable name>=function(){
//
//
}

How it this different than following declaration?

<object name>.<variable name>=function(){
//
//
}

How are prototype functions different than normal functions in javascript ?

• javascript

• 1 Please re-phrase into a real question that can be answered. – gahooa Commented Dec 9, 2009 at 3:10
• 3 @gahooa: Why do you think this question can't be answered. It might be very high level, but it is still a question. You can always edit it to make it more clear. No need to down vote this simply because of grammatical mistakes... – Josh Commented Dec 9, 2009 at 3:13
• stackoverflow.com/questions/186244/… – John Paulett Commented Dec 9, 2009 at 3:13
• Some doggone good stuff here: stackoverflow.com/questions/1595611/… – Crescent Fresh Commented Dec 9, 2009 at 3:17

3 Answers 3

Prototype functions are instance functions, whilst normal functions are "static" functions. Functions declared on class's prototype will available on all instances of that class.

var MyClass = function(){
};
MyClass.staticFunction = function(){alert("static");};
MyClass.prototype.protoFunction = function(){alert("instance");};

MyClass.staticFunction(); //OK
MyClass.protoFunction (); //not OK

var myInstance = new MyClass ();
myInstance.staticFunction(); //not OK
myInstance.protoFunction (); //OK

functions declared on a base object's prototype are inherited by all instances of that object type.

For example..

String.prototype.foo = function () {
  return 'bar';
};

Now, every string will have the function foo() available.

'test'.foo(); // returns 'bar'

Read more about prototype-based inheritance here

Matt and Igor have already provided enough code samples, but one of the best articles (short, correct and to the point) that you can read is Prototypal Inheritance, by Douglas Crockford.

There are also lots of different ways to facilitate inheritance through popular libraries (Dojo, Prototype, etc)