平滑滚动

smoothScroll.js

; (function (window, $) {
      'use strict';

      var $scrollTo;
      var timer = null;
      var scrollTop = 0;

      window.onscroll = function () {
        scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
      };

      $scrollTo = function (target) {
        var destOffsetTop = 0;
        if (typeof target == 'string') {
          destOffsetTop = target;
        } else if (typeof target.offset == 'function') {
          var destOffsetTopObj = target.offset();
          destOffsetTop = destOffsetTopObj.top;
        } else if (target.top != undefined) {
          destOffsetTop = target.top;
        } else {
          throw 'param target error!';
        }

        clearInterval(timer);
        timer = setInterval(function () {
          var now = scrollTop;
          var speed = (destOffsetTop - now) / 10;
          speed = speed > 0 ? Math.ceil(speed) : Math.floor(speed);
          if (scrollTop == destOffsetTop) {
            clearInterval(timer);
          }
          document.documentElement.scrollTop = scrollTop + speed;
          document.body.scrollTop = scrollTop + speed;
        }, 30);
      };

      if ($ != undefined) {
        $.fn.scrollTo = $.scrollTo = $scrollTo;
      }

      window.$scrollTo = $scrollTo; //支持$scrollTo('300px');纯js用法
    })(window, window.jQuery || window.Zepto || undefined);