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;
};

Wouldn't it be nice if you could somehow apply lines 2-4 seamlessly to every constructor function?

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.