How to declare a static variable in Javascript [duplicate]

Answer 1

For a static you can assign a property to the function object itself;

Person.counter = 0;

And within the constructor increment with;

Person.counter += 1;

You can also check-if-undefined and create Person.counter within the constructor

function Person(){
   if (typeof Person.counter === 'undefined')
      Person.counter = 0;
   else
      Person.counter += 1;
   ...