$(document).ready(function(){... $(function(){...//等待dom元素加载完毕

<!-- 引入 jQuery -->
<script src="../scripts/jquery.js" type="text/javascript"></script>
<script type="text/javascript">
//等待dom元素加载完毕.
$(function(){
    alert("Hello World!");
});
</script>

<!-- 引入 jQuery -->
<script src="../scripts/jquery.js" type="text/javascript"></script>
<script type="text/javascript">
//等待dom元素加载完毕.
$(document).ready(function(){
    alert("Hello World!");
});
</script>