I am trying to filter the form value to change some links color and background but this is incorrect

```
$("a").filter('a[href$='"'+username'"]').css("background-color", "#ff0000");   

```

Here is the HTML example

```
 <body>
    <div class="main"> 
    <p> 
    Lorem Ipsum is simply dummy text of the printing and typesetting industry.
    <a href="u=3153">user1</a>, <a href="u=31532">user2</a>, <a href="u=231532">user3</a>, <a href="u=11111">user4</a>, <a href="u=22222">user5</a>.
    </p> 
    </div>
    <div id="buttons">
    <form method="post" action="">
    Username:<br /> 
    <input type="text" value="" class="userform"  id="user" maxlength="15"/>
    <br />
    <input type="submit" value="   Submit   "  class="submit"/>
    </div>
    </body>   

```

And this is the jquery

```
$(document).ready(function(){
    $("body").keyup(function() 
    {
    var username = $("#user").val();
    $("a").filter('a[href$='"'+username'"]').css("background-color", "#ff0000");
    });
    });

```

My problem is that I can't "put" the form value in the keyup function