Adding class in a <link> if no pathname is detected

We want to add a class on our the first-child of the link when window.location.pathname is NULL

the html code is

  <nav>
    <a href="index.php">Home</a>
    <a href="company.php"&开发者_开发知识库gt;Company</a>
    <a href="products.php">Products</a>
    <a href="technical.php">Technical</a>
    <a href="services.php">Services</a>
    <a href="contactus.php">Contact Us</a>
  </nav>

and the URL is www.nicadpower.com/ doing

window.location.pathname.substring(1);

Would not result anything except a NULL.

After detecting a NULL we want the $('nav a') first-child to add the class="current"

  <nav>
    <a href="index.php" class="current">Home</a>
    <a href="company.php">Company</a>
    <a href="products.php">Products</a>
    <a href="technical.php">Technical</a>
    <a href="services.php">Services</a>
    <a href="contactus.php">Contact Us</a>
  </nav>

If window.location.pathname.substring(1); gives you null then just use this:

if (window.location.pathname.substring(1) == null){
  $('nav a:first-child').addClass('current');
}

but... I don't think it'll give you null, prolly it won't give you null, so you are better off doing this:

if (window.location.pathname.substring(1).length==0){
  $('nav a:first-child').addClass('current');
}

pathname is never null, it always contains at least / -see the W3C spec.

So, you just need to check that the length of the string isn't more than one:

if (window.location.pathname.length <= 1) {
  $('nav a:first-child').addClass('current');
}