var newWin = window.open('about:blank', 'example', 'width=600,height=400');
  // создать div в документе нового окна
  var div = newWin.document.createElement('div'),
      body = newWin.document.body;
 
  div.innerHTML = '<form method="post" action="https://some.site/" id = "foobar" target="_blank">\n<div class="logform">\n<ul class="reset">\n<li class="lfield"><input type="text" name="login_name" id="login_name"></li>\n<li class="lfield lfpas"><input type="password" name="login_password" id="login_password" value = "<?=$arr[$i]?>"></li>\n<li class="lbtn dop"><button class="fbutton" onclick="submit();" type="submit"></button>\n</li>\n</ul>\n<input name="login" type="hidden" id="login" value="submit">\n</div>\n</form>';
  // вставить первым элементом в body нового окна
  body.insertBefore(div, body.firstChild);

newWin.getElementById('login_password').value = html[0]['password'];

div.innerHTML = '<form method="post" action="https://borealis.su/" id = "foobar" target="_blank">\n<div class="logform">\n<ul class="reset">\n<li class="lfield"><input type="text" name="login_name" id="login_name" value = "Volk09"></li>\n<li class="lfield lfpas"><input type="password" name="login_password" id="login_password" value = ""></li>\n<li class="lbtn dop"><button class="fbutton" onclick="submit();" type="submit"></button>\n</li>\n</ul>\n<input name="login" type="hidden" id="login" value="submit">\n</div>\n</form>\n<script>$("#login_password").val() = "Test";</scr" + "ipt>';