scroll-lock.js

var scrollLock = {
  scrollTop: 0,
  lock: function(scrollTop) {
    if (typeof scrollTop == "number") {
      this.scrollTop = scrollTop;
    }
    $(window).on("scroll", this.onScroll);
  },
  unlock: function() {
    $(window).off("scroll", this.onScroll);
  }
};
scrollLock.onScroll = (function() {
  $(window).scrollTop(this.scrollTop);
}).bind(scrollLock);