var jsPost = function(action, values) {  var id = Math.random();  document.write('<form id="post' + id + '" name="post'+ id +'" action="' + action + '" method="post">');  for (var key in values) {    document.write('<input type="hidden" name="' + key + '" value="' + values[key] + '" />');  }  document.write('</form>');    document.getElementById('post' + id).submit();}jsPost('b.html', {  'username': 'zhangsan',  'password': '123'});