AUGMENTING TYPES

JavaScript allows the facility for binding methods and other properties to built-in types, such as strings, numbers, and arrays. Strings, just like any other object, have prototypes. You can also augment String with convenience methods. For example, String has no method for converting the string “false” or “true” to a Boolean. You can add this capability as the following code demonstrates:

String.prototype.boolean = function() {
  return “true” == this; 
};
 
var t = 'true'.boolean();
var f = 'false'.boolean();
 
console.log(t);
console.log(f);
 
true
false

Code snippet is from string-boolean.txt

Admittedly, it’s annoying to have to redundantly type prototype every time you want to add a method. Douglas Crockford has a neat bit of code for getting around this, which augments the Function.prototype with a method called, method (please pardon the redundancy.) This is shown in the following code sample.