gistfile1.js

var Field = function() {
 this.validate = function() {
   // ...
 }
}
 
// the form holds many fields but they both have the same named public method "validate"
var FormValidator = function() {
  var fields = [];
  
  // ...
  // store field instances in above array
  // ...
  
  this.validate = function() {
    // loop through all instances of a Field
   
    // calling a method on field instance
    fields[i].validate();
  }
}
 
// so i can do one or both of the following
new FormValidator().validate();
new Field().validate();