jquery谷歌调试

$(document).ready(function () {
    $(".new_cont ul li:first a").hover(function () {
        $(".newimg img").animate({width:"80%",height:"80%"},1000);
    });
}

<div class="mydemo width mar">
    <button id="left">«</button> <button id="right">»</button>
    <div class="block"></div>
</div>            //html代码

js代码
<script type="text/javascript">
$(".mydemo #left").click(function () {
        $(this).animate({marginLeft:'+50px'},"slow");
    });
    $(".mydemo #right").click(function () {
        $(this).animate({ marginLeft: '-50px' }, "slow");
    });
</script>