jQuery 返回头部[顶部] 代码

 var main_left = Math.round($(".main").offset().left+980)+"px";
var back_top_ele = "<a href='javascript:;' id='back_top'></a>";
var back_top_sty = {width:"15px", height:"60px", bottom:"100px", left:main_left, position:"fixed", display:"none", background:"red" };
$("body").append(back_top_ele);
$("#back_top").css(back_top_sty);
$(window).scroll(function(){
if( $(window).scrollTop() > 200 ){
if ($.browser.msie && ($.browser.version == "6.0") && !$.support.style) {
$("#back_top").css({ display:"block", position:"absolute", top:$(window).scrollTop()+450+"px"});
}else{
$("#back_top").css({ display:"block", position:"fixed"});
}
}else{
$("#back_top").hide();
}
});
$(window).resize(function(){
if($(window).width() <= 1000){
main_left = $(window).width()-20+"px";
}else{
main_left = Math.round($(".main").offset().left+980)+"px";
}
$("#back_top").css("left",main_left);
});
$("#back_top").click(function(){
$("html, body").animate({scrollTop:0}, 500);
return false;
});