Show error on pressing back/forward button

Question

我有一个登录页面，当登录的用户按下后退按钮时，该页面应该显示错误而不是显示登录页面，并且应该在前进按钮上应用相同的内容。

Answer 1

window.onbeforeunload event will fire when the user leaves the page.

var prevURL = document.referrer;

window.onbeforeunload = function() {
  if(prevURL == 'provide your login page URL here') {
    return "Error message";  // alert
    //or do whatever you want
  }
};

Note that this event will fire when the user leaves the page for anyway.