$.fn.scrollTo = function(options) { 
  var defaults = { 
    toT: 0, //滾動(dòng)目標(biāo)位置 
    durTime: 500, //過渡動(dòng)畫時(shí)間 
    delay: 30, //定時(shí)器時(shí)間 
    callback: null //回調(diào)函數(shù) 
  }; 
  var opts = $.extend(defaults, options), 
    timer = null, 
    _this = this, 
    curTop = _this.scrollTop(), //滾動(dòng)條當(dāng)前的位置 
    subTop = opts.toT - curTop, //滾動(dòng)條目標(biāo)位置和當(dāng)前位置的差值 
    index = 0, 
    dur = Math.round(opts.durTime / opts.delay), 
    smoothScroll = function(t) { 
      index++; 
      var per = Math.round(subTop / dur); 
      if (index >= dur) { 
        _this.scrollTop(t); 
        window.clearInterval(timer); 
        if (opts.callback && typeof opts.callback == 'function') { 
          opts.callback(); 
        } 
        return; 
      } else { 
        _this.scrollTop(curTop + index * per); 
      } 
    }; 
  timer = window.setInterval(function() { 
    smoothScroll(opts.toT); 
  }, opts.delay); 
  return _this; 
}; 
 
//調(diào)用 
 $("body").scrollTo({ toT: 0 });