当进入网站内页时加载导航相应的样式

//当进入网站内页时加载导航相应的样式
<script type="text/javascript">
    var txtjbo = new Array("", "about", "exhibitors", "visitor", "news");
    var objpath = window.location.href;
    var id = 0;
    for (var i = 0; i <= txtjbo.length; i++) {
        if (objpath.toLowerCase().indexOf(txtjbo[i]) > 0) {
            id = i;
        }
    }
    for (var i = 0; i <= txtjbo.length; i++) {
        if (i == id) {
            if (document.getElementById("mynav" + i) != null) {
                document.getElementById("mynav" + i).className = "nav_on";//当前页的样式
            }
        }
        else {
            if (document.getElementById("mynav" + i) != null) {
                document.getElementById("mynav" + i).className = "nav_off";//其他页的样式
            }
        }
    }

</script>