function PreAndNextPage()
{
    var reg1= /<a href=\"([-\w\.\/\?]+)\"?>上一篇<\/a>/igm;
    if (window.document.body.innerHTML.search(reg1) >= 0) {
	    var PREVIOUS_PAGE = RegExp.$1;
    }
    var reg2 =/<a href=\"([-\w\.\/\?]+)\"?>下一篇<\/a>/igm;
    if (window.document.body.innerHTML.search(reg2) >= 0) {
	    var NEXT_PAGE = RegExp.$1;
    }

    if (typeof PREVIOUS_PAGE == "string" || typeof NEXT_PAGE == "string" || typeof home_PAGE == "string") {
	    document.onkeydown = function() {
		    switch (event.srcElement.tagName) {
			    case "INPUT":
			    case "TEXTAREA":
			    case "SELECT":
				    break;
			    default:
				    if (event.keyCode == 37 && typeof PREVIOUS_PAGE == "string") {
					    window.location.href = PREVIOUS_PAGE;
				    }
				    else if (event.keyCode == 39 && typeof NEXT_PAGE == "string") {
					    window.location.href = NEXT_PAGE;
				    }
		    }
	    }
    }
}