Javascript-页面打印函数

<script type="text/javascript">
        function preview() {
            bdhtml = window.document.body.innerHTML;
            sprnstr = "<!--startprint-->";
            eprnstr = "<!--endprint-->";
            prnhtml = bdhtml.substr(bdhtml.indexOf(sprnstr) + 17);
            prnhtml = prnhtml.substring(0, prnhtml.indexOf(eprnstr));
            window.document.body.innerHTML = prnhtml;
            window.print();
        }
</script>
<!--startprint-->
 **打印内容**
<!--endprint-->