js打印事件

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();
    //prnform.htext.value=prnhtml;
    //prnform.submit();
    //alert(prnhtml);
}