Adding two values together

gistfile1.html

<p>
    <input type="text" name="input-a"> 
    <span>+</span>
    <input type="text" name="input-b">
<p>
 
<button type="button" class="calculate">Add them up</button>
 
<script src="http://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<script type="text/javascript">
    // wait for someone to click on a button
    $(".calculate").click(function() {
        // get the value of the input, and show it in a dialog
        var a = parseFloat( $("input[name='input-a'").val() );
        var b = parseFloat( $("input[name='input-b'").val() );
        alert( a + b );
    });  
</script>