stuarthallows

// PROTOTYPE

// Modularize code into re-usable objects, take variables and functions out of global namespace,
// functions loaded into memory once whereas the state is all held in the objects, can override 
// functions through prototyping.
// Drawbacks: heavy use of 'this' keyword and the constructor is separate from the prototype definition.

var Calculator = function(eq) {
  // Variables defined in constructor and are unique to each instance.
	this.eqCtl = document.GetElementById(eq);