Enable smooth scroll jumping inside a web page to any given element, position or anchor(id). Written in plain JavaScript without jQuery. (tested on Chrome > 21, Firefox > 28, IE >= 8) https://jsfiddle.net/6xfd9dr8/

smooth-scroll.js

var scroll = {
  iterr: 30, // miliseconds
  tm: null,
  reset_timer: function () { // reset
    if (this.tm) {
      clearTimeout(this.tm);
      this.tm = null;
    }
    this.iterr = 30;
  },
  realtop_of: function (el) {
    var elm = el;
    var realTop = 0;
    do {
      realTop += elm.offsetTop;
      elm = elm.offsetParent;
    } while (elm);
    return realTop;
  },
  pagescroll: function () {
    var yOff = window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop;
    return yOff;
  },
  go2top: function () {
    return scroll.go2elem(document.body);
  },
  go2id: function (id) {
    var targetEl = document.getElementById(id);
    return scroll.go2elem(targetEl);
  },
  go2elem: function (targetEl) {
    var eOff = targetEl.offsetTop;
    var tOff = this.realtop_of(targetEl.parentNode);
    return scroll.go2pos(eOff, tOff);
  },
  go2pos: function (eOff, tOff) {
    // scroll to tha element with the given id.
    // eOff : beginning point
    // tOff : terminus point
    this.reset_timer();
    var pOff, scrVal, pos, dir, step;

    pOff = this.pagescroll();
    if (pOff === null || isNaN(pOff) || pOff === 'undefined') pOff = 0;

    scrVal = eOff - pOff; // scroll amount

    if (scrVal > tOff) {
      pos = (eOff - tOff - pOff);
      dir = 1;
    }
    if (scrVal < tOff) {
      pos = (pOff + tOff) - eOff;
      dir = -1;
    }
    if (scrVal !== tOff) {
      step = ~~((pos / 4) + 1) * dir;
      this.iterr = (this.iterr > 1) ? this.iterr - 1: 0;

      window.scrollBy(0, step);

      this.tm = window.setTimeout(function () {
        scroll.go2pos(eOff, tOff);
      }, this.iterr);
    }
    if (scrVal === tOff) {
      this.reset_timer();
    }
  }
};