JS pre-function boilerplate

avoiding-global-scope-pollution-in-constructors.js

var ClassName = function(){
  if(this === window){
    throw new Error('ClassName must always be called with the "new" prefix');
  }

  this.status = null;
};

If this is what you want, why not just use strict mode, which would prevent this from happening (i.e. it throws an error) or just code defensively, i.e.

function ClassName() {
  if (this === window) return new ClassName;

  this.status = null;
}

This way you can either use your function as a constructor or a factory :).

You can also set up jshint to warn about Constructor functions (capitalised functions) being called without new.