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I get confused with the terminology, constructor, in javascript , it always show in javascript
document or internet article.

Question-1

For example,
function test() {}
var b= new test()
where test() is function constructor always described in those article   What is constructing ?

Question-2

var mesg="hello";
console.log(mesg); //hello
var mess = new String("hello") ;
console.log(mesg) //String{0:"h",1:"e",2:"l",3:"l",4:"o",Length:5}
console.log(mesg.constructor);  //function String(){ [ native code ] }

What is mesg constructing from mesg.constructor ? What there is [native code] meaning ?
What is native meaning in javascript( i.e. bulit-in code or function) ?

Question-3.

Could we show all String function code inside instead of [native code], OR it is not allowed on browser ?

Question-4.

Is it exactly same meaning of constructor in javascript as in C++ such using "::"

Please advise

Rwniceing

The constructor property returns the constructor function for an object. This enables you to decide the type of the function object.

constructor can be viewed as a prototype from which an object is created. You can retrieve the constructor for a function object and it can be used if you need to relate a function object to its creation.

In a way it is similar to the constructor concept that is seen in other OO languages like C++ and Java.

Take a look at
http://javascript.info/tutorial/constructor