How to declare a static variable in Javascript [duplicate]

Question

In the following code, I would like to have a counter to keep track of the number of Person objects created. This code is not doing so, how would I accomplish that?

function Person(){     this.name = "Peter";     this.counter = this.counter + 1;     alert(this.counter); }  Person.prototype.counter = 0;  var p1 = new Person; var p2 = new Person; 

Answer 1

function Person(){     this.name = "Peter";     Person.counter++;     alert(Person.counter); }  Person.counter = 0;  var p1 = new Person(); var p2 = new Person(); 

Make the "static" variable a property of the Person function, rather than the prototype, and use Person instead of this inside the constructor.

This is possible because JavaScript functions are first-class (i.e. they are objects), so can have properties of their own.

Here's a working example of the above code.