We want to include a maps from Google Maps API in our document. The documentation tells to initialize the map with a function called by the onload() event of the body.
body.addEventListener("load", init(), false);
That init() is saying run this function now and assign whatever it returns to the load event.
What you want is to assign the reference to the function, not the result. So you need to drop the ().
body.addEventListener("load", init, false);
Also you should be using window.onload and not body.onload
addEventListener is supported in most browsers except IE 8.