js 平滑定位

<script type="text/javascript">

            function intval(v){
                v = parseInt(v);
                return isNaN(v) ? 0 : v;
            } // ?取元素信息
            function getPos(e){
                var l = 0;
                var t = 0;
                var w = intval(e.style.width);
                var h = intval(e.style.height);
                var wb = e.offsetWidth;
                var hb = e.offsetHeight;
                while (e.offsetParent) {
                    l += e.offsetLeft + (e.currentStyle ? intval(e.currentStyle.borderLeftWidth) : 0);
                    t += e.offsetTop + (e.currentStyle ? intval(e.currentStyle.borderTopWidth) : 0);
                    e = e.offsetParent;
                }
                l += e.offsetLeft + (e.currentStyle ? intval(e.currentStyle.borderLeftWidth) : 0);
                t += e.offsetTop + (e.currentStyle ? intval(e.currentStyle.borderTopWidth) : 0);
                return {
                    x: l,
                    y: t,
                    w: w,
                    h: h,
                    wb: wb,
                    hb: hb
                };
            } // ?取??条信息
            function getScroll(){
                var t, l, w, h;
                if (document.documentElement && document.documentElement.scrollTop) {
                    t = document.documentElement.scrollTop;
                    l = document.documentElement.scrollLeft;
                    w = document.documentElement.scrollWidth;
                    h = document.documentElement.scrollHeight;
                }
                else
                    if (document.body) {
                        t = document.body.scrollTop;
                        l = document.body.scrollLeft;
                        w = document.body.scrollWidth;
                        h = document.body.scrollHeight;
                    }
                return {
                    t: t,
                    l: l,
                    w: w,
                    h: h
                };
            } // ?点(Anchor)?平滑跳?
            function scroller(el, duration){
                if (typeof el != 'object') {
                    el = document.getElementById(el);
                }
                if (!el)
                    return;
                var z = this;
                z.el = el;
                z.p = getPos(el);
                z.s = getScroll();
                z.clear = function(){
                    window.clearInterval(z.timer);
                    z.timer = null
                };
                z.t = (new Date).getTime();
                z.step = function(){
                    var t = (new Date).getTime();
                    var p = (t - z.t) / duration;
                    if (t >= duration + z.t) {
                        z.clear();
                        window.setTimeout(function(){
                            z.scroll(z.p.y, z.p.x)
                        }, 13);
                    }
                    else {
                        st = ((-Math.cos(p * Math.PI) / 2) + 0.5) * (z.p.y - z.s.t) + z.s.t;
                        sl = ((-Math.cos(p * Math.PI) / 2) + 0.5) * (z.p.x - z.s.l) + z.s.l;
                        z.scroll(st, sl);
                    }
                };
                z.scroll = function(t, l){
                    window.scrollTo(l, t)
                };
                z.timer = window.setInterval(function(){
                    z.step();
                }, 13);
            }
        </script>

 <div class="test">
            <a name="header_1" id="header_1"></a>
            <strong onclick="javascript:scroller('header_4', 800);">header_1 --> header_4</strong>
            <p>
            </p>
        </div>
        <div class="test">
            <a name="header_2" id="header_2"></a>
            <strong onclick="javascript:scroller('header_5', 800);">header_2 --> header_5</strong>
            <p>
            </p>
        </div>

另外一种方式是使用jquery比较简单一些!

我们知道html有锚点定位的效果，那么如何实现平滑的定位效果呢？下面由68ecshop的技术来为您详细解答

<script type="text/javascript" src="http://code.hs-cn.com/jquery/jquery-1.7.1.min.js"></script>

<div id="top" class="append_box mb20">
    平滑跳转到底部：<a href="#bottom" class="smooth">滑到底部</a>
</div>
<div id="appendBox" class="append_box">
   <img width="950" height="931" src="http://www.dubai.com/images/upload/Image/201407210943470ffuoj.jpg" /><br />
    <img width="950" height="1000" src="http://www.dubai.com/images/upload/Image/20140721094432t9j0kt.jpg" />
</div>
<div id="bottom" class="append_box mb20">
    平滑回到顶部：<a href="#top" class="smooth">回到顶部链接</a>
</div>

<script>
$(".smooth").click(function(){
    var href = $(this).attr("href");
    var pos = $(href).offset().top;
    $("html,body").animate({scrollTop: pos}, 1000);
    return false;
});
</script>

//技术解答：

//class="smooth"：我们自己定义的一个class名称，目的是js调用该标签

//href="#top"：top是要定位的标签ID名称

//$("html,body").animate({scrollTop: pos}, 1000)：1000 是滑动的时间，我们可以自己调整

刷新页面之后平滑定位到指定位置

$("html, body").scrollTop(0).animate({scrollTop: $(".top-20").offset().top});