In a class if private data member is declared then how to set data to that private data member? 

Accept parameters are capabilities of functions in JavaScript.

A class can have any number of constructors. If a class have more than one constructor, we call it as the constructor is overloaded.

Constructor chaining is the process of calling one constructor from another constructor with respect to current object.

Within same class: It can be done using this() keyword for constructors in same class

From base class: by using super() keyword to call constructor from the base class.

"eval" is not a keyword and is can be used as variable.

Function: A Function is a block of statement which perform some operation.

Declaring the function before using the function in program is known as implicit declaration of the function.

For Example::

int bar(void); // function (forward) declaration

int main(void) {

bar(); // bar was declared, the compiler has all the info

return foo(123); // foo not yet known; impl. decl. warning

}

// not previously declared function definition

int foo(int a) {

return a;

} 

// previously declared function definition

int bar() {

return 321;

}

Yes, it is possible to nest functions in javascript.