Code Illusion

It happens sometime that you need to cache some data which has produced by a complex operation. Caching data helps you not to do repeat the complex operation. Caching the results of an operation is also known as Memoization. Followings are too example of this pattern. var setCache = function (param,val) {        setCache.cache[param] =val;        return setCache.cache[param];  }; setCache.cache={}; or you can just save the result of a function inside the  function: var setCache = function (param) {        if (!setCache.cache[param]){           var res;           //do the complex and heavy operation            //here and assign the  result to 'res'           setCache.cache[param] =res;        }        return setCache.cache[param]; }; setCache...

With Chaining Pattern you can call object methods one after the others without assigning the result to other variables or break them in multiple statement or lines. For example: myobj.func1().func2(1,2,3).func3('fsnjk'); This pattern is only useful when object functions do not have to special return so, this pattern can  implemented by returning this in each object function. For example: var myelm={         hide: function(second){                 //code for hiding                  return this;         },         fadeIn: function(second){                 //code for fading                  return this;         } }; myelm.hide(1).fadeIn(2);

Javascript does not have special syntax for private members however they can be implement by using closure in object constructor and using wrap function in object literal. Examples below shows how private members can be implemented. Example 1. Object Constructor function Grocery(){     //private     var type='fruit';          //public     this.getType=function(){         return type;     } } var orange=new Grocery(); alert(orange.type); //undefined alert(orange.getType()); //fruit Example 2. Object  Literal var orange; (function(){     //private     var type="fruit";          //public     orange={         getType:function(){             return type;         }     }; }()); alert(orange.getType...

In the following example although function foo seems longer, but in minified version it is rather smaller than the boo function.This is because compilers will rename local variables name and declaring the dependency at the beginning of the foo function allows smaller code after minification. function boo() {     alert(App.namespace.f1);     alert(App.namespace.f2);     alert(App.namespace.f3); } /* minified boo alert(App.namespace.f1);alert(App.namespace.f2);alert(App.namespace.f3) */ function foo() {     var namespace = App.namespace;     alert(namespace.f1);     alert(namespace.f2);     alert(namespace.f3); } /* minified foo  var a=App.namespace;alert(a.f1);alert(a.f2);alert(a.f3) */

There are differences how functions defined in javascript. In javascript all variable regardless of where in the function body declared will get hoisted to the top of function, this also includes  functions which are defined inside the function but there is a difference  how the functions has been declared. the example below shows this difference. function foo() { alert('global foo'); } function bar() { alert('global bar'); } function hoistMe() { console.log(typeof foo); // "function" console.log(typeof bar); // "undefined" foo(); // "local foo" bar(); // TypeError: bar is not a function // function declaration function foo() { alert('local foo'); } //unnamed function expression var bar = function () { alert('local bar'); }; } hoistMe(); in this example foo will get hoisted to the top with it’s definition but only declaration of bar has hoisted to the top.

Is the on which can dynamically be created, destroyed at runtime during the execution of program,and pass as an argument to other functions. I n some languages like javascript and python functions are also first class objects. Ex. Passing function as an argument in Python:            >>> def op(a,b,fun):             return fun(a,b)     >>> def sum(a,b):             return a+b     >>> op(1,2,sum)     3 Ex. Dynamically defined function in javascript: var supriseMe = function () { alert("Boo!"); supriseMe = function () { alert(" boooooooo!"); }; }; // using the self-defining function supriseMe(); // Boo! supriseMe(); // boooooboo!