Untitled

// index.html

<html>
    <head>
        <title>Todo List</title>
        <style>
            .complete { text-decoration:line-through; }
        </style>
    </head>

    <body>
        <ul></ul>
        <input type="text" x-webkit-speech />
        <button>Submit</button>
    </body>

    <script type="text/javascript" src="jquery.js"></script>
    <script type="text/javascript" src="main.js"></script>
</html>

// main.js

var $list = $('ul');
var $input = $('input');
var $button = $('button');

$button.click(function() {
    var task = $input.val();
    var $item = $('<li class="incomplete">' + task + '</li>');
    $item.click(toggleTask);
    $list.append($item);
    $input.val('');
});

function toggleTask() {
    $(this).hasClass('incomplete') ? $(this).attr('class', 'complete')
                                   : $(this).attr('class', 'incomplete')
}