js-defined function is executed immediately after

// 使用 ! 、+ 、- 等运算符
;!function(win){
  console.log(win);
}(window);

// 使用括号，推荐这种写法，因为没有返回值参与运算
(function(win){
  console.log(win);
})(window);
// 或
(function(win){
  console.log(win);
}(window));