Js闭包乱象

var obody = document.querySelector('body');
(obody.onclick = function(){
    alert(555)  //555
})()

var obody = document.querySelector('body');
obody.onclick = (function(){
    alert(555)  //555
})()

var obody = document.querySelector('body');
obody.onclick = function(){
    alert(555)  //555
}()