I'm following the book "javascript definitive guide" and i found this example

PHP Code:
// Register the function f to run when the document finishes loading.
// If the document has already loaded, run it asynchronously ASAP.
function onLoad(f) {
if (
onLoad.loaded// If document is already loaded
window.setTimeout(f0); // Queue f to be run as soon as possible
else if (window.addEventListener// Standard event registration method
else if (
window.attachEvent// IE8 and earlier use this instead
// Start by setting a flag that indicates that the document is not loaded yet.
onLoad.loaded false;
// And register a function to set the flag when the document does load.
onLoad(function() { onLoad.loaded true; }); 

I do not understand what means
onLoad(function() { onLoad.loaded = true; });

It seem like an abbreviated synthax of "addEventListener" method, but doing some proofs it never is executed...
So, in this snippet i can't find the utility because no listener are initialized and no of his function will be executed