如何在页面更改时保持子菜单打开

Question

I have this JS code for my menu:

$(document).ready(function () {
  $('#nav > li > a').click(function(e){
     if ($(this).attr('class') != 'active'){
       $('#nav li ul').slideUp();
       $(this).next().slideToggle();
       $('#nav li a').removeClass('active');
       $(this).addClass('active');
     }
  });
});

what is the best way to make the sub menus stay open when the page is changed - maybe using cookies or sessions?

I have created a jsfiddle here so you can see the full html and css etc: http://jsfiddle.net/bMkEj/

Answer 1

It can be done using HTML5 LocalStorage .

In the click handler, save the active menu text to localStorage:

$('#nav > li > a').click(function(e){
   ...
   localStorage.setItem("activeSubMenu", $(this).text());
});

On page load, read the localStorage and expand the menu (if found):

$(document).ready(function(){
    var activeItem = localStorage.getItem("activeSubMenu");
    if(activeItem){
        $('#nav > li > a').filter(function() {
            return $(this).text() == activeItem;
        }).slideToggle();
    }
});

Answer 2

Pass a query parameter when you load the page and use it to select the appropriate nav item:

HTML

<ul>
    <li id="foo"><a href="index.html?nav=foo">Foo</a>
        <ul>
            <li>Foo 1</li>
            <li>Foo 2</li>
        </ul>
    </li>
    <li id="bar"><a href="index.html?nav=bar">Bar</a>
        <ul>
            <li>Bar 1</li>
            <li>Bar 2</li>
        </ul>
    </li>
    <li id="baz"><a href="index.html?nav=baz">Baz</a>
        <ul>
            <li>Baz 1</li>
            <li>Baz 2</li>
        </ul>
    </li>
</ul>

JS (assumes jQuery)

$(document).ready(function() {
    var query = decodeURIComponent(window.location.search);
    var matches = query.match(/nav=([^&]*)/);
    var id = matches[1];
    $('#' + id + ' ul').slideDown();
});

Answer 3

If you're running PHP, or any other server-end language, you could add the active class to the active element.

EDIT: If you're just running JS you might be able to parse the url (window.location.href) and use that to set the active class.