Develop Reference

Passing a window object into Javascript namespace

I'm trying to better understand namespacing in javascript and found an example of a javascript Immediately-invoked Function Expression that is taking the window object as a parameter. Here is the code from it:
var CG = CG || {};
CG.main = (function(window) {
var FOCAL_LENGTH = 8.0;
var context, width, height, startTime;
var init = function() {
var element = document.getElementById("canvas1");
context = element.getContext("2d");
width = element.width;
height = element.height;
startTime = (new Date()).getTime() / 1000.0;
tick();
}
var original_onload = window.onload || function() {};
window.onload = function() {
original_onload();
CG.main.init();
}
return {
init: init,
draw: draw_shape,
clear: clear_canvas
};
}(window));
At the end of the namespace definition, there is a line with window in parenthesis which I am confused as to the functionality of. I think that the purpose of adding the parameter of window to the end of the definition is to bind the global window variable to the namespace which will then add different properties to the window, but I can't really be sure.
In another example there is a random variable name passed into the definition of a namespace, and at the end of the namespace definition, the actual name of the namespace is passed as a parameter:
var namespace = namespace || {};
// here a namespace object is passed as a function
// parameter, where we assign public methods and
// properties to it
(function( o ){
o.foo = "foo";
o.bar = function(){
return "bar";
};
})(namespace);
console.log(namespace);
So there are really a couple of questions here:
What is the functionality of passing a parameter at the end of the namespace definition?
If my intuition for how this all works is incorrect, what is the general structure for this kind of namespace creation javascript?
Clearly I'm very new to this so any help would be appreciated, thanks.

I will try to explain this as well as I can but my understanding of it comes from Kyle Simpson. He's awesome, you should look him up. :-D
You are asking a question about immediately invoked function expressions (IIFE), passing arguments to them, and why someone would do that.
First, the reason IIFEs are being used in this context is to restrict the scope of variables.
This is important because as programs become larger and many pieces are added on you can easily have conflicts from one variable to another.
app.js could have
variable = "thing";
and shortly after somethingelse.js could have
variable = "not thing";
That is a huge problem. It is avoided in javascript by creating "modules" or functions that immediately run and run once.
That way, the variables and methods you create in your function don't "pollute the global scope/namespace."
BUT, what if you NEEDED or WANTED something to be available on the global window object?
Well, you could do that by adding it to the "window" which is the global scope in javascript.
(function Module(window){
var _thing = "private thing that only exists in this function";
window.thing = _thing;
//IS NOW AVAILABLE GLOBALLY AND EXPLICITLY ON WINDOW OBJECT
//window.onload you can wait for DOM/page before running the rest
})(window);
You also could have named it anything you wanted inside your function:
(function niftyModule(global){
global.variable = "nifty text!";
})(window)
This becomes especially important when you are using multiple libraries.
For some reason, everyone likes to use "$" as the representation of their library so you can access their private methods (which are really just functions inside an IIFE too! (its a really popular way to build good stuff).
So, what if you are using jQuery and 2 other libraries that also use $ to access their public methods/api??
Easy, you can assign which one you want to assign what variable inside your function/module scope by passing it in as an argument!
(function NiftyModule(window, $){
//Now, every time you use $ in here it means jQuery and not something else!
})(window, jQuery);
It is important to play around with functions and scope. Build some variables in different ways.
For example, is....
var text = "nifty text";
the same as
text = "nifty text";
How about if you do the same thing inside functions? How do those two versions differ?
Also, get used to building your own programs in IIFEs and properly restricting the scope of the code you are writing.
You can also return objects from functions which have the methods and variables you want to access globally on them without adding them to the window object.
It is complicated at first but in the future it saves you a lot of trouble and bugs!
Finally, In your example of:
//initialize a global variable called namespace. If this already
//existed then assign it the previous values. If not, make it an empty
//object.
var namespace = namespace || {};
//pass namespace into an IIFE. Within the IIFE refer to namespace as "o"
(function( o ){
//assign a variable to namespace
o.foo = "foo";
//assign a method to namespace
o.bar = function(){
return "bar";
};
})(namespace);
//now when you log namespace it will have those properties.
console.log(namespace);

Variable privacy in Javascript's behaviour delegation pattern

Since my last question, I've been studying Javascript's prototype model and trying to get rid of the OOP vision I inherited from other languages (pun slightly intended).
I went back to basics and read Crookford's Javascript: The Good Parts, along with You Don't Know JS material and decided to stick with the so called behaviour delegation.
Restructuring my previous example implementing behaviour delegation and namespacing, I wrote:
var GAME = {};
(function(namespace) {
var Warrior = {};
Warrior.init = function(weapon) {
this.setWeapon(weapon);
};
Warrior.getWeapon = function() {
return this.weapon;
};
Warrior.setWeapon = function(value) {
this.weapon = value || "Bare hands";
};
namespace.Warrior = namespace.Warrior || Warrior;
})(GAME);
(function(namespace) {
var Archer = Object.create(namespace.Warrior);
Archer.init = function(accuracy) {
this.setWeapon("Bow");
this.setAccuracy(accuracy);
};
Archer.getAccuracy = function() {
return this.accuracy;
};
Archer.setAccuracy = function(value) {
this.accuracy = value;
};
namespace.Archer = namespace.Archer || Archer;
})(GAME);
So, everytime I copy a new Archer object:
var archer1 = Object.create(GAME.Archer);
only this object will be created, conserving memory.
But what if I don't want to expose "accuracy" attribute? The attribute would only increase by calling a "training()" method or something similar. I tried to use var accuracy inside the anonymous function, but it turns into kind of static variable, all instances of Archer would share the same value.
The question: Is there any way to set a variable as private while still keeping behaviour-delegation/prototypal pattern?
I do know of functional pattern as well, Here I succesfully achieved variable privacy, at the cost of memory. By going functional, every new "archer" instance generates a new "Warrior" and then a new "Archer". Even considering that Chrome and Firefox have different optmizations, testings on both report that the Delegation/Prototypal pattern is more efficient:
http://jsperf.com/delegation-vs-functional-pattern
If I go with the pure-object delegation pattern, should I just forget the classic encapsulation concept and accept the free changing nature of properties?

I would try to answer your question with something that is slightly different then this one that tells you how to use a library.
Different in that it will(hopefully) give you some ideas of how can we tackle the problem of private vars in OLOO ourselves. At least to some extent, with our own code, no external lib needed, which could be useful in certain scenarios.
In order for code to be cleaner I've striped your anonymous wrapper functions, since they are not related to problem in any way.
var Warrior = {};
Warrior.warInit = function (weapon){
this.setWeapon(weapon);
}
Warrior.getWeapon = function(){
return this.weapon;
}
Warrior.setWeapon = function (value){
this.weapon = value || "Bare hands";
}
var Archer = Object.create(Warrior);
Archer.archInit = function (accuracy){
this.setWeapon("Bow");
this.setAccuracy(accuracy);
}
Archer.getAccuracy = function (pocket) {
return pocket.accuracy;
}
Archer.setAccuracy = function (value, pocket){
pocket.accuracy = value;
}
function attachPocket(){
var pocket = {};
var archer = Object.create(Archer);
archer.getAccuracy = function(){
var args = Array.prototype.slice.call(arguments);
args = args.concat([pocket]);
return Archer.getAccuracy.apply(this, args)
};
archer.setAccuracy = function(){
var args = Array.prototype.slice.call(arguments);
args = args.concat([pocket]);
return Archer.setAccuracy.apply(this, args);
};
return archer;
}
var archer1 = attachPocket();
archer1.archInit("accuracy high");
console.log(archer1.getAccuracy()); // accuracy high
archer1.setAccuracy("accuracy medium");
console.log(archer1.getAccuracy()); // accuracy medium
Test code above here. (and open your browser console)
Usage
1 ) General practice in OLOO about naming functions on different levels of prototype chain is apposite from OOP. We want different names that are more descriptive and self documenting, which brigs code that is cleaner and more readable. More importantly, by giving different names we avoid recursion loop:
Archer.init = function(accuracy, pocket){
this.init() // here we reference Archer.init() again, indefinite recurson. Not what we want
...
}
Archer.archInit = fucntion (accuracy, pocket){ // better,
this.warInit() // no name "collisions" .
}
2 ) We've created an attachPocket() function that creates internal variable pocket. Creates new object with Object.create() and sets it's prototype to point to Archer. Pause. If you notice, functions that required a private var we have defined so that each of them take one more parameter(pocket), some use just pocket. Here is the trick.
By making wrapper functions like archer.setAccuracy(), archer.getAccuracy()
... we can create closures and call directly functions that need
private var (here pocket) and pass it to them as an argument.
Like so:
function AtachPocket(){
...
var pocket = {};
archer.setAccuracy = function(){
var args = Array.prototype.slice.call(arguments);
args = args.concat([pocket]); // appending pocket to args
return Archer.setAccuracy(this, args);
};
...
}
Essencially by doing this we are bypassing what would have been a normal search for functions in prototype chain, just for functions that have need for a private var. This is what "call directly" refers to.
By setting the same name for a function in archer("instance") like it is in prototype chain (Archer) we are shadowing that function at the instance level. No danger of having indefinite loops, since we are "calling directly" like stated above. Also by having the same function name we preserve the normal, expected behaviour of having access to same function in an "instance" like it is in a prototype chain. Meaning that afther var archer = Object.create(Archer) we have access to function setAccuracy like we would if it had been normal search for function in prototype chain.
3 ) Every time attachPocket() is invoked it creates a new "instance" that has those wrapper functions that pass a pocket argument (all as an internal detail of implementation). And therefore every instance has own, unique, private variable.
You would use functions in an "instance" normally:
archer1.archInit("accuracy high"); // Passing needed arguments.
// Placed into pocked internally.
archer1.getAccuracy(); // Getting accuracy from pocket.
Scalability
Up to now all we have is function that "attaches a pocket" with hardcoded values like Archer.setAccuracy, Archer.getAccuracy. What if we would like to expand prototype chain by introducing a new object type like this var AdvancedArcher = Object.create(Archer), how the attachPocket is going to behave if we pass to it AdvancedArcher object that might not even have setAccuracy() function? Are we going to change attachPocket() each time we introduce some change in prototype chain ?
Let's try to answer those questions, by making attachPocket() more general.
First, expand prototype chain.
var AdvancedArcher = Object.create(Archer);
AdvancedArcher.advInit = function(range, accuracy){
this.archInit(accuracy);
this.setShotRange(range);
}
AdvancedArcher.setShotRange = function(val){
this.shotRange = val;
}
More generic attachPocket.
function attachPocketGen(warriorType){
var funcsForPocket = Array.prototype.slice.call(arguments,1); // Take functions that need pocket
var len = funcsForPocket.length;
var pocket = {};
var archer = Object.create(warriorType); // Linking prototype chain
for (var i = 0; i < len; i++){ // You could use ES6 "let" here instead of IIFE below, for same effect
(function(){
var func = funcsForPocket[i];
archer[func] = function(){
var args = Array.prototype.slice.call(arguments);
args = args.concat([pocket]); // appending pocket to args
return warriorType[func].apply(this, args);
}
})()
}
return archer;
}
var archer1 = attachPocketGen(Archer,"getAccuracy","setAccuracy");
archer1.advInit("11","accuracy high");
console.log(archer1.getAccuracy()); // "accuracy high";
archer1.setAccuracy("accuracy medium");
console.log(archer1.getAccuracy());
Test the code here.
In this more generic attachPocketGen as first argument we have a warriorType variable that represents any object in our prototype chain. Arguments that may fallow are ones that represent names of functions that need a private var.
attachPocketGen takes those function names and makes wrapper functions with same names in archer "instance". Shadowing, just like before.
Another thing to recognise is that this model of making wrapper functions and using apply() function to pass variables from closures is going to work for functions that use just pocket, functions that use pocket and other variables, and when ,of course, those variables use the relative this reference in front of them.
So we have achieved somewhat more usable attachPocket, but that are still things that should be noticed.
1) By having to pass names of functions that need private var, that usage implies that we(attachPocketGen users) need to know whole prototype chain (so we could see what functions need private var). Therefore if you are to make a prototype chain like the one here and just pass the attachPocketGen as an API to the programmer that wants to use your behaviour-delegation-with-private-variables, he/she would had to analyse objects in prototype chain. Sometimes that is not what wee want.
1a) But we could instead, when defining our functions in prototype chain (like Archer.getAccuracy) to add one property to them like a flag that can tell if that function have need for a private var:
Archer.getAccuracy.flg = true;
And then we could add additional logic that checks all functions in prototype chain that have this flg and fills the funcsForPocket.
Result would be to have just this call:
var archer1 = attachPocketGen(AdvancedArcher)
No other arguments except warriorType. No need for user of this function to have to know how prototype chain looks like, that is what functions have need for a private var.
Improved style
If we are to look at this code:
Archer.archInit = function (accuracy){
this.setWeapon("Bow");
this.setAccuracy(accuracy);
}
We see that it uses "pocket" function setAccuracy. But we are not adding pocket here as last argument to it because setAccuracy that gets called is shadowed version, the one from instance. Becouse it will be called only from an instance like so archer1.archInit(...) That one is already adding a pocket as last argument so there is on need to. That's kinda nice, but the definition of it is:
Archer.setAccuracy = function (value, pocket){ ...
and that can be confusing when making objects in prototype chain like Archer.archInit above. If we look the definition of setAccuracy it looks like we should it. So in order not have to remember that we don't have to add pocket as last arg in functions (like archInit) that use other pocket functions, maybe we should to something like this:
Archer.setAccuracy = function (value){
var pocket = arguments[arguments.length -1];
pocket.accuracy = value;
}
Test the code here.
No pocket as last argument in function definition. Now it's clear that function doesn't have to be called with pocket as an argument wherever in code.
1 ) There are other arguably minor stuff to refer to when we think about more general prototype chain and attachPocketGen.Like making functions that use pocket callable when we dont wan't to pass them a pocket, that is to toggle pocket usage to a function, but in order not to make this post too long, let's pause it.
Hope this can give you view ideas for solution to your question.

Motivation for mutiple layers of referencing? - Code Academy JavaScript

I am working through the JavaScript track on CodeAcademy and have encountered a question on Objects II -> Introduction to Objects II -> Private Methods (25/30). I'm not understanding the motivation behind things pointing to things, that point to other things. If we are trying to get to the value of a variable why not refer to it more directly? For example
var d refers to var c
and
var c refers to var b
and
var b refers to var a
Why do this rather than referring to var a initially? Why create variables b, c, and d at all? Anyway in Private Methods - 25/30 the heart of the matter is below. *Note - I put the exhaustive/exact code at the very bottom
**var bankBalance = 7500;** // Located within the Person class
**var returnBalance = function()** // Create returnBalance method which returns
**return bankBalance;** // the bankBalance above
t**his.askTeller = function() {** // Create the askTeller method which calls
**return returnBalance;** // returnBalance method above
**var myBalanceMethod = john.askTeller();** // create a variable named myBalanceMethod
// which equals the value for askTeller method above
**var myBalance = myBalanceMethod();** // create a variable named myBalance which
// equals the value for myBalanceMethod method above
**console.log(myBalance);** // logs to the console the value of myBalance
This all seems like a lot of trouble. What is the motivation to go through all this trouble instead of a more direct reference to bankBalance?
Below I have included my EXACT code (note - it works just fine I just don't understand to reasoning behind the multiple layers)
**function Person(first,last,age) {
this.firstname = first;
this.lastname = last;
this.age = age;
var bankBalance = 7500;
var returnBalance = function() {
return bankBalance;
};
// create the new function here
this.askTeller = function() {
return returnBalance;
};
}
var john = new Person('John','Smith',30);
console.log(john.returnBalance);
var myBalanceMethod = john.askTeller();
var myBalance = myBalanceMethod();
console.log(myBalance);**

Referencing something through another name isn't demonstrated properly in the example (which is why real-world examples are so necessary and so praised when used).
When we assign a variable to something we already have a reference for, such as:
var cc = Components.Classes;
we can do it for brevity, such as above. Writing cc as opposed to Components.classes can make the code a lot clearer and easier to read, as long as the context is clear. Once you start using APIs, the DOM or complex objects, the usefulness of this becomes quite clear. In this case, I can replace all my Components.Classes references, such as:
Components.classes["#mozilla.org/messenger;1"];
with
cc["#mozilla.org/messenger;1"];
Much better - especially when you have to chain these:
var os = Components.classes["#mozilla.org/observer-service;1"]
.getService(Components.interfaces.nsIObserverService);
becomes:
var os = Cc["#mozilla.org/observer-service;1"].getService(Ci.nsIObserverService);
Now it fits in a single line and is much easier to vgrep/tokenize-with-your-eyes.
Another advantage is assigning, for example, as single definition of a function to two or more objects:
function _start() { /* start monitoring */ }
function _stop() { /* stop monitoring */ }
/* ... code ... */
process_observer.start = _start;
process_observer.stop = _stop;
memory_monitor.start = _start;
memory_monitor.stop = _stop;
In this example, assuming we've written our _start and _stop functions to be agnostic of what our object monitors and can fit any monitoring object, we can write our function once and still assign it to each object separately so we can call process_observer.start() instead of start(process_observer) which would requite acting on the object rather than having the object act ( the former might involve exposing data and methods we would otherwise want to keep hidden, to prevent errors and promote clarity - it also might prevent us from using certain design patterns ). These are of course a matter of preference, design approaches and perspective, but never underestimate readability and clarity in code. Also, if we change _start or _stop is changes for all objects that use them, instead of requiring manual changes. A common usage case is having different implementations for different platforms or browsers and having the proper function assigned to all objects that use it, at initialization, where we detect what where running on.
Also, you might have noticed I didn't use parenthesis () when I assigned my functions to the object owned variables - when you do it like your example:
myBalance = myBalanceMethod();
you're not assigning myBalanceMethod to myBalance - you're calling myBalanceMethod (because of the ()) and assigning it's return value to myBalance - very big trap. People trip over this all the time when assigning click handlers in html elements.
To be honest, as I said in the beginning, the example is terrible - there is no reason write that code that way and, as you've already found out yourself, it makes it harder to understand rather than easier, which is the whole point of aliasing variables and functions and being able to assign them so freely.

How to use scope in JavaScript for Function constructor?

If I were to make a new function using the Function constructor, how could I give it a non-temporary scope to access besides window (meaning the scope only has to be evaluated once, not every time the function is called)? The purpose is to construct multiple variables that require some pretty costly calculations, and I don't want to reconstruct them every time the function is called, but I also don't want to store them in window. Any ideas?

You could bind your function to the specific context using bind keyword:
var context = {};
var f = new Function("args", "return this").bind(context);
f(); // context
Since bind is defined in ECMA 5th, it may not be present in all browsers, here's a workaround

For the above described purpose, you use static functions. You cannot prevent scope from being evaluated at every call, because this is the way JavaScript works, but you can speed it up by not having window in the scoping chain.
var namespace = {};
namespace.someMethod = function() {
// do something here.
};
Now anywhere in your code, you can call that method by using namespace.someMethod();. Just be careful. The above is a static method. You can call it without instantiating. But you MUST NOT use this.property inside a static function. It is a potentially very dangerous operation, as it may give an extension access to the global object and basically un-restricted permissions.
And the above is a static JavaScript method. It does not have window in the scoping chain.
Here's how to create a constructor using the same pattern. When you want to use a constructor, you always instantiate before using. For that you have the new keyword.
var namespace = {};
namespace.coordinate = function(x, y) {
this.x = x;
this.y = y;
};
namespace.coordinate.prototype.addCoordinates = function() {
return this.x + this.y;
};
Now anywhere in your code you can do:
var coordinateObject = new namespace.coordinate(5,10);
// you have created a new instance.
alert(coordinateObject.addCoordinates());// will alert 15;
// now you can make as many as you want. They will behave as instances.
// This means they do not interfere with each other in any way.
// They just have the same properties and methods, but the instance values
// Can be entirely different.
var secondCoordinateObject = new namespace.coordinate(10, 25);
alert(secondCoordinateObject.addCoordinates());// will output 35.
You have successufully created an instance of your namespace.coordinate class. Using the pattern I gave you, you can replicate almost the entire functionality of Java or C or any other Object Oriented language.

var yourNamespace = {
func1: function() {
},
func2: function() {
}
};
...
yourNamespace.func1();
you can call the function that you want by calling the function from name space like this yourNamespace.func1();

The ever-growing method of creating, storing, hiding, revealing, and grouping variables & functions is through the magic of "closures", Javascript's most powerful and yet unsung feature:
var groupObj = (function (setUp) {
// maintained by reference, hidden
var _priVar = setUp * 2;
// maintained by reference, revealed (through returned object)
var _pubVar = 8;
var _pubFunc = function (x) {
_priVar += x;
_pubVar += x;
}
var lostVar = setUp * 99; // not referenced, hidden, so evaporates!
return {
'pubVar' : _pubVar,
'pubFunc' : _pubFunc
}
}(4)); // runs immediately with 4 as setUp, revealing pubVar & pubFunc
Then...
groupObj.pubFunc(7); // runs public function, adds 7 to both variables
alert('public variable: ' + groupObj.pubVar); // alerts public variable
A closure occurs whenever there is a function inside of another function. A variable inside of the outter function will be maintained so long as it is referenced by the inner function, kind of a "no-mans land" where a variable is forced to exist by a reference to it from a lower scope, but is hidden from the higher scope due to the innate principles of Javascript.
There are a few other ways to use closures, replacing the object constructor, one-off conflict-free private functions, and more. There are many posts here about them.

Is my javascript coding style following best-practice?

What is the 'best practise' with regard to coding style.
Should I use _ for private members?
Should I use this._privateMember?
Please re-write my code in proper style if its wrong:
(function()){
var _blah = 1;
someFunction = function() {
alert(_blah);
};
someOtherFunction = function {
someFunction();
}
}();

I would read this and incorporate any part you agree with:
http://javascript.crockford.com/code.html
You do not have to agree with all of it

I don't think there is one. Use a prefix if you think it helps.
I use _ for private members because it distinguishes them which can be quite helpful in Javascript when you have variables coming from all over the place. But they do clutter the code a bit.

I don't use _ for variables that are declared using var. I do however, use _ to denote object members that shouldn't be access directly.
Some people (who are strange in my opinion :P), also prefix variables with a $ if it contains a jQuery object.
As long as you are consistent with what you do, there are no problems.
Aside from just the code you're showing now, you should use Capital Letters to distinguish constructor functions, and camelCase to name instances of objects.
function Foo (val) {
this.set(val);
};
Foo.prototype.get = function () {
return this._dontTouchMePlease;
};
Foo.prototype.set = function(val) {
this._dontTouchMePlease = parseInt(val, 10);
};
var aFoo = new Foo(6);

I think that its generally accepted that if a variable name starts with a _, you probably shouldn't touch it (accept in dire cirumcstances and even then, two keys and special codes should be provided).
If I'm remembering my Crockford correctly, you'll want to put var in front of the two inner functions, otherwise they will be implicit globals. If you want them to be globals, then that's moot. Either way, your second inner function declaration should probably end in a semicolon. This might be a misformating thing, but I think its generally accepted that the bodies of functions are indented one more level in. Also, I've never seen the (function()){/* stuff */}(); construction before, but that says pretty much nothing.
I'd write it these ways - one for if your just declaring a function and another for if your using an anonymous function and immediately applying it to get a result, because I don't which one you're trying to do (again, if you want the inner functions to be global, then this won't be what you intended):
//function declaration
var myFunction = function () {
var _blah = 1;
var someFunction () {
alert(_blah); //or console.log(_blah); for debugging purposes
};
var someOtherFunction () {
someFunction();
};
};
//using a one-of to assign a result
/* NOTE: if you are using this version, myResult will be undefined
(at least given the functions you provided), but like I said,
I don't recognize the construction you provided, and am therefore
assuming that you meant one of these two, which could be a perfectly
falacious assumption, and in that case, my apologies
*/
var myResult = function () {
var _blah = 1;
var someFunction () {
alert(_blah);
};
var someOtherFunction () {
someFunction();
};
}();
BTW, (and I don't want to overstep) Crockford's "JavaScript: The Good Parts" is a stellar reference for JavaScript syntax. He also has, on his website a JavaScript style guide of sorts (though I don't know how widely followed it is). Link is: http://javascript.crockford.com/code.html

I also use the "_" in c# for private/protected members. It is a fast way to see if the variable is a member-variable or not. And you can access it faster with code-completion because you don't get in mess with the public members (private: _blah , public property: Blah).
But are there any private members in javascript anyway? I think every variable defined as member is accessible from the outside.
So you don't have a public wrapper for the private member. And that means the "_" is a bit a overhead and the same can be achieved with "this.".

I prefer you to use the following stuffs which is preferably used around the world programmers.. see below
i = Int
f = Float
o = Object
r = Return
a = Array
e = Element
g = Global declaration
hook = a function which can be used for hooking with other functions
call = a function which can be used for making call from client to server system
sync = a function which can be used for SYNC
and so on.. you can prefix on your coding...