console.log(typeof null); // object  

console.log(NaN === NaN); // false

console.log(navigator.userAgent);  
// Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-us) AppleWebKit/531.21.8 (KHTML, like Gecko) Version/4.0.4 Safari/531.21.10  

Mosaic/0.9     // browser name / version number

Mozilla/2.02 [en] (Win95; I)     // browser name / version / encryption

MSIE/3.0 (Win95; U)

Mozilla/2.0 (compatible; MSIE 3.0; Windows 95)

// Create a function that will call a function with the name equal to parameter fn.  
function foo(fn) {  
    if (typeof fn === "function") {  
        fn();  
    }  
}  
  
// Create an object with a property and a method.    
var bar = {  
    barbar : "Hello, World!",  
    method  : function() {  
        alert(this.barbar);  
    }  
};  
  
bar.method(); // Alerts Hello, World!  
foo(bar.method); // If we call the foo function add pass the "bar.method" method, it somehow alerts "undefined."  
foo(function() { bar.method(); }); // alerts Hello, World, after  

!!(0); // false  
!!(false); // false  
!!(''); // false  
!!(null); // false  
!!(undefined); // false  
!!(NaN); // false  

// braces on the right  
return {  
  foo : bar  
};  
  
// braces on their own line  
return    
{  
  foo : bar  
};  

var foo = function() {  
      
    return {  
        a : 'b'  
    };  
      
}();  
  
alert(foo.a); // b

return  {  
    a : 'b'  
};  

return
{  
    a : 'b'  
};  

return; // JS incorrectly adds this semicolon.  
{  
    a : 'b'; // It'll add a semicolon here as well, because it doesn't realize that this is an object.  
};