javascript get function body

Question

I have a function e.g.

var test = function () {alert(1);}

How can I get the body of this function?

I assume that the only way is to

Answer 1

IF(!!!) you can get the toString(), then you can simply take the substring from the first indexOf("{") to the lastIndexOf("}"). So, something like this "works" (as seen on ideone.com):

var test = function () {alert(1);}

var entire = test.toString(); // this part may fail!
var body = entire.substring(entire.indexOf("{") + 1, entire.lastIndexOf("}"));

print(body); // "alert(1);"

Answer 2

var fn1 = function() {};
var fn2 = function() { alert("lol!"); };

Function.prototype.empty = function() {
var x = this.toString().match(/\s*function\s*\w*\s*\(.*?\)\s*{\s*}\s*;?\s*/);
return x != null;
};

alert(fn1.empty()); // true
alert(fn2.empty()); // false

' Solução proposta pelo Paulo Torres no grupo A.P.D.A. no facebook.