This is my first attempt to write shorthand if statements however am befuddled by why the expanded versions don't work quite the way I imagined they would.

Code 1 - Does not work

if(document.getElementById == true) {
        alert("The document object model is supported by: " + navigator.appName);   
    }

Code 2 - Does work

if(document.getElementById != false) {
            alert("The document object model is supported by: " + navigator.appName);   
        }

Code 3 - The shorthand that does work

 if(document.getElementById) {
            alert("The document object model is supported by: " + navigator.appName);   
        }

Why is that if I expand the shorthand in 3 to the first code sample not work and why does it work if I have it equal to != false?