Develop Reference

Which JavaScript design pattern is this?

I'm not sure which JavaScript design pattern I'm following. Can someone please help shed some light on it?
var masonrySupport = ({
large__videos__support: function() {
$('.masonry-container .largeRec').find('.itemMasVideo').parent().addClass('item_largeRec_video_height');
},
smallRec__videos__support: function() {
$('.masonry-container .smallRec').find('.itemMasVideo').parent().addClass('item_smallRec_video_height');
},
init: function() {
this.large__videos__support(),
this.smallRec__videos__support()
}
})
masonrySupport.init();

There are two "patterns" I can see here.
Using self invoking closure to isolate scope.
(function($) {
// Code here
})(jQuery);
Helps mitigate the creation of accidental global variables.
(Kind) the module pattern, where you create an object with a bunch of methods on it, and call init(). I prefer to self invoking closure version of it. The Revealing Module Pattern.

The pattern you are using is called the Module Pattern, and it is one of the most important patterns in JavaScript. You outer wrapper creates an anonymous scope that provides privacy and state to the code that you place inside it.
(function($) {
// Everything in here is private and stateful
// and we can access jQuery through the imported $ variable
})(jQuery);
To your scope, you're also passing the global jQuery object. This method is called global import, and is faster and clearer than accessing the implied global from within your scope.
Inside your scope, you are creating an API that is accessible through the masonrySupport variable, making it a Revealing Module Pattern.

I don't see this as a design pattern in the strict sense of terminology. May be associated with the module pattern, but it needs to return something to be accessible outside of it's inner scope. It's only a self executing function invoked inside a scope which in this case is jQuery. This is used in many jquery plugins. You isolate the scope of the self executing function to a specific - lets say - domain.
This can be found on the first declaration:
(function($) {
...
})(jQuery);
By closuring the function you are guarding the functions and variables declared inside the scope to a specific domain, in this way eliminating the possibility to accidentally override or redeclare some function or variable declared in the global scope. It's a common practice to isolate the scope from the global object which in Javascript world is the Object or on DOM context is window.
And it continues with the self executing function:
$(function() {
...
})

Effectively what is being done here is, once the document loads, execute two functions - 'large__videos__support' and 'smallRec__videos__support.'
Let's understand how it is being achieved,
Firstly it is Immediately-Invoked Function Expression (IIFE) in action. This pattern is often used when trying to avoid polluting the global namespace, because all the variables used in the function are not visible outside its scope.
(function($) {
...
})(jQuery);
Short hand of $( document ).ready() is being used. More here.
$(function() {
...
});
Thirdly, you are initializing one object being referenced by 'masonrySupport' and calling its method 'init.'

In JS, this is called and Immediately Invoked Function Expression (IIFE), and is known as the module pattern.
However in jQuery this pattern is used to create jQuery Plugins. I advise you to follow the best practices to make it work.
Check that jsfiddle to get you started.
Below the JS part:
(function( $ ) {
$.fn.masonrySupport = function( option ) {
if ( option === "large") {
this.find('div.itemMasVideo').parent().addClass('item_largeRec_video_height');
}
if ( option === "small" ) {
this.find('div.itemMasVideo').parent().addClass('item_smallRec_video_height');
}
return this;
};
}( jQuery ));
$( 'div.masonry-container.largeRec' ).masonrySupport( "large" );

Function inside the AngularJS Controller

I have code snippet in which there is a Angular Modular Controller, but there is a function inside the same controller and with a call, which is raising doubt in my mind that is this way of coding allowed in Javascript or Angular? If Yes then how does it read it? See the below code format I have:
obj.controller('CartController',function($scope){
$scope.totalCart = function(){
var total = 10;
return total;
}
function calculate(){
...Some Logic..
}
$scope.$watch($scope.totalCart, calculate);
)};
Please help me to understand that is this type of function definition and call within a controller allowed in Angular/Javascript?

The calculate() is a private function -- it is only accessible in the scope of CartController. If you do not need to make use of your function in the view it is good idea to make it private. It says that it is not intended to be used in the view, so if someone else will be working with this code should think twice before use it in the view. Moreover: from within calculate you have access to all objects that are accessible in the scope of the CartController (including objects passed to CartController as parameters).
Function declared in this way is a proper JS function, which means you can get reference to it by its name. Sometimes it is thought to be more readable if you declare / create your function in advance and only then assign them to properties of some other object (in this case $scope):
function someFn (...) { ... }
function someOtherFn (...) { ... }
...
$scope.someFn = someFn
In the above snippet the intentions are very clear: make someFn accessible, while keep someOtherFn private.
Btw. declaring functions like: function nameFn(...){...} is called function statement; you can very similarly do it like: var nameFn = function(...) {...} (so called function expression). There is a slight difference between those -- basically it is illegal:
someFn();
var someFn = function(...) {...}
whereas, this works:
someFn();
function someFn(...) {...}
Sometimes you are forced to use this pattern, look e.g. at my answer to this question.

$scope.launch = function (which) {
};
var _func = function () {...}

The definition is allowed, it has the same affect as
$scope.$watch($scope.totalCart, function(){..some logic...})

Access a javascript variable from a function inside a variable

Hello i have the following issue i am not quite sure how to search for it:
function(){
var sites;
var controller = {
list: function(){
sites = "some value";
}
}
}
So the question is how to access the sites variable from the top defined as
var sites
EDIT:
Here is a more complete part. i am Using marionette.js. i don't want to define the variable attached to the Module (code below) variable but keep it private to the Module, hope that makes sense. Here is the code that works:
Admin.module("Site", function(Module, App, Backbone, Marionette, $, _ ) {
Module.sites = null;
Module.Controller = {
list: function (id) {
Module.sites = App.request("site:entities");
}
};
});
and i would like instead of
Module.sites=null;
to do
var sites;
That sort of thing does make a difference right? Because in the first case i would be defining an accessible variable from outside where as the second case it would be a private one. i am a bit new to javascript so please try to make it simple.

if you are looking for global access, just declare the variable outside the function first, make your changes to the variable inside the function, then you can get the value whenever you need it.

I have found some info on this: sadly what i am trying to do doesn't seem possible.
Can I access a private variable of a Marionette module in a second definition of that module?
So i guess i have to do _variable to make developers know its private.

Disclaimer: I have no experience using Marionette, however, what you're describing sounds very doable.
One of the most powerful (in my opinion) features of JavaScript is closures. What this means is that any function declared from within another function has access to the variables declared in the outer function.
For example:
var func;
function foo() {
var answer = 42;
func = function () {
// I have access to variable answer from in here.
return answer++;
};
}
// By calling foo(), I will assign the function func that has access "answer"
foo();
// Now I can call the func() function and it has access to the "answer"
// variable even though it was in a scope that doesn't exist anymore.
// Outputs:
// 42
// 43
console.log(func());
console.log(func());
What this means is that if you declare var sites from within your module definition function as you described, you should have access to it from within any of your inner anonymous functions. The only exception is if Marionette is re-writing your functions (by using the Function function and toString()), which seems unlikely but possible.
Your original example should would as described, my suspicion is that there is something else going wrong with the code that is unrelated to your scope.

The way of good scoping in JavaScript

I am not a really good JavaScript user but I can get things done with it. I am not proud of the code I have written in JavaScript, so I decided to change that. Here is my first step:
I am trying create my own library for a project and the below is the initial structure.
window.fooLib = {};
(function (foo) {
"use strict";
foo.doSomeStuff = function(param1) {
console.log(new AccommProperty(param1));
}
//some internal function
function AccommProperty(nameValue) {
var _self = this;
_self.name = nameValue;
}
}(fooLib));
I used immediately invoked function expression here to initialize my variable. In this case it is fooLib.
I am not sure if I should do some other things to make window.fooLib more safe. I mean it can be overridden by any other code which will run after my code if I understand JavaScript correctly.
What are your thoughts?

If you want to prevent overwriting your variables, you may use Object.defineProperty() with writable:false, configurable:false. In your case:
(function () {
"use strict";
var foo = {};
//some internal function
function AccommProperty(nameValue) {
var _self = this;
_self.name = nameValue;
}
foo.doSomeStuff = function(param1) {
console.log(new AccommProperty(param1));
}
Object.defineProperty(window, "foolib", {value:foo});
}());
Still, there is no good reason for that. It would need EcamScript 5.1 to work, and there are no shims around; maybe something with getters/setters to prevent overwriting with the = operator.
But also, there should be no need to make your library un-overwritable. Just don't use code on your site that overrides the lib. Or maybe someone even wants to overwrite your functions with another, better lib with the same interface?
If the question is about a library to be shared, with possible namespace conflicts to others, you may have a look at jQuery.noConflict.

Every JavaScript object can be overriden. This is the nature of JavaScript and it is impossible to change it. So you cannot make your code safe in that sense.
As for selfinvoked functions: you should use them when you want to have local variables but viisible to all your functions. So in your case AccommProperty is such variable. Defining doSomeStuff inside scope makes no difference unless doSomeStuff will use variables defined inside scope.
So when you want to hide variables from user and/or you need globals and you are affraid of name conflicts use selfinvoked functions.

I am not sure if I should do some other things to make window.fooLib more safe. I mean it can be overridden by any other code which will run after my code if I understand JavaScript correctly.
You could try making window.fooLib a local variable instead. Using closures and nested functions one can emulate a namespace where you can put all your data instead of putting it into the global scope or attaching it to window object:
(function() {
// all functions nested in foo() have access to fooLib.
fooLib = {}
fooLib.doSomeStuff = function(param1) {
console.log(param1);
console.log(fooLib);
}
//some internal function
function AccommProperty() {
console.log(fooLib);
}
}());
See Javascript Closures: Encapsulating Related Functionality for more details.

Enclosing external jQuery script

I have an external JavaScript file that will be used on pages with lots of other scripts. My script involves a lot of jQuery that listens for events, and by design, I have many global vars declared. I've been reading best practice articles, and a lot is said about 'polluting the global namespace' and inadvertent script interaction.
What's the best way to enclose (encapsulate?) my JavaScript file so that:
I can still access some of the
variables outside of the enclosure
The jQuery event listeners will
function properly
I'm not at liberty to disclose the code, so even general responses are appreciated. Additionally, any other tips on making scripts less vulnerable to other scripts on the page are welcome.
I've found enclosure styles for regular JavaScript, but does the use of jQuery complicate this?

Generally what this boils down to is encapsulating your objects into a "namespace". I use quotes there because the term is not an official semantic in JavaScript, but rather one that is achieved through basic object encapsulation.
There are several ways to do this, and it ultimately comes down to personal preference.
One approach is to just use a basic JS object, and keep everything in it. The name of the object should be semantic and give the object some meaning, but otherwise it's purpose is to just wrap your own code and keep it out of the global namespace.
var SomeName = {
alpha: 1,
beta: {a: 1, b: 2},
gamma: function(){
SomeName.alpha += 1;
}
}
In this case, only SomeName is in the global namespace. The one downside to this approach is that everything inside the namespace is public, and you have to use the full namespace to reference an object, instead of using 'this' - e.g. in SomeName.gamma we have to use SomeName.alpha to reference the contents of alpha.
Another approach is to make your namespace a function with properties. The nice feature of this approach is you can create 'private' variable through closures. It also gives you access to closured functions and variables without full namespace referencing.
var SomeName = (function(){
var self = this;
var privateVar = 1;
var privateFunc = function() { };
this.publicVar = 2;
this.publicFunc = function(){
console.log(privateVar);
console.log(this.publicVar); // if called via SomeName.publicFunc
setTimeout(function(){
console.log(self.publicVar);
console.log(privateVar);
}, 1000);
};
}();
The other bonus of this approach is it lets you protect the global variables you want to use. For example, if you use jQuery, AND another library that creates a $ variable, you can always insure you are referencing jQuery when using $ by this approach:
var SomeName = (function($){
console.log($('div'));
})(jQuery);

One method is to namespace like this:
var MyNamespace = {
doSomething: function() {},
reactToEvent: function() {},
counter: 0
}
You will just have to refer to the functions or variable using the namespace: MyNamespace.reactToEvent. This works fine for separating what you would normally have in the window (where all the confrontation is).

You can wrap your code in an anonymous Javascript function and only return what you want to expose to the outside world. You will need to prefix var to your global variables so that they remain only in the scope of the anonymous function. Something like this:
var myStuff = (function() {
var globalVar1;
var globalVar2;
var privateVar1;
function myFunction() {
...
}
function myPrivateFunction() {
...
}
return {
var1: globalVar1,
var2: globalVar2,
myFunction: myFunction
};
})();
Now you can access myStuff.var1 and myStuff.myFunction().

Two ways to encapsulate or limit namespace pollution
1) Create one global var and stuff everything you need into it.
var g = {};
g.somevar = "val";
g.someothervar = "val2";
g.method1 = function()
{
// muck with somevar
g.somevar = "something else";
};
2) For inline scripts, consider limiting the scope of the functions called.
<script>
(
function(window)
{
// do stuff with g.somevar
if(g.somevar=="secret base")
g.docrazystuff();
}
)(); // call function(window) then allow function(window) to be GC'd as it's out of scope now
</script>

I just started using RequireJS and have now become obsessed with it.
It's basically a dependency management system in a modular JavaScript format. By doing so you can virtually eliminate attaching anything to the global namespace.
What's nice is that you only reference one script on your page require.js then tell it what script to run first. From there it is all magic...
Here's an example implementation script:
require([
//dependencies
'lib/jquery-1.6.1'
], function($) {
//You'll get access to jQuery locally rather than globally via $
});
Read through the RequireJS API and see if this is right for you. I'm writing all my scripts like this now. It's great because at the top of each script you know exactly what you dependencies are similar to server-side languages - Java or C#.

This is a common practice with jQuery plugins for the same reasons you mention:
;(function ($) {
/* ... your code comes here ... */
})(jQuery);
This is an immediate function. If you declare your "global" variables inside, they will be local to this closure (still "global" for the code you create inside). Your event listeners will work inside here too, and you will still be able to reach real global variables.