Extending javascript functions

Method 1/

function Animal(name){
    this.name = name;
}
Animal.prototype.talk = function(){
    console.log("My name is "+this.name);
}
var a = new Animal("Brendan Eich");
a.talk();
var json = '{name: "Tim Berners-Lee"}'
var b = eval(b);
$.extend(b, Animal.prototype);
b.talk();

Method 2/

// declare function foo
var foo = function (a) { alert(a); };
// modify function foo
foo = new Function (
  "a",
  foo.toSource()
    .replace("alert(a)", "alert('function modified - ' + a)")
    .replace(/^function[^{]+{/i,"")  // remove everything up to and including the first curly bracket
    .replace(/}[^}]*$/i, "")  // remove last curly bracket and everything after
);

Method 3/

function m1(){

  alert('Initial function')

} 

webBrowse1.Navigate(@"javascript:m1=new function(alert('Replace after.'))");