requireJS模块化实现返回顶部功能的方法详解

require.config({
  paths:{
    jquery:'jquery'
  }
});
requirejs(['jquery','backtop'],function($,backtop){
  $('#top').backtop({
    mode:"move",
    pos:100,
    dest:500,
    speed:20000
  })
});

/**
 * Created by Administrator on 2016/3/24.
 */
define(["jquery","scrollTo"],function($, scroll){
  function backtop(el,opts){
    this.opts = $.extend({},backtop.default,opts);
    this.$el = $(el);
    this.scroll = new scroll.scrollTo({
      dest:this.opts.dest,
      speed:this.opts.speed
    });
    this._checkPostion();
    if(this.opts.mode == "move"){
      this.$el.on("click", $.proxy(this._move,this))
    }else{
      this.$el.on("click", $.proxy(this._go,this))
    }
    $(window).on("scroll", $.proxy(this._checkPostion,this))
  };
  backtop.prototype._move = function(){
    this.scroll.move()
  };
  backtop.prototype._go = function(){
    this.scroll.go()
  };
  backtop.prototype._checkPostion = function(){
    if($(window).scrollTop() > this.opts.pos){
      this.$el.fadeIn();
    }else{
      this.$el.fadeOut();
    }
  }
  $.fn.extend({
    backtop:function(opts){
      return this.each(function(){
        new backtop(this,opts);
      })
    }
  });
  backtop.default = {
    mode:"move",
    pos:100,
    dest:0,
    speed:800
  }
  return{
    backtop:backtop
  }
})

define(['jquery'],function($){
  function scrollTo(opts){
    this.opts = $.extend({},scrollTo.DEFAULTS,opts);
    this.$el = $("html,body");
  }
  scrollTo.prototype.move = function(){
    if($(window).scrollTop() != this.opts.dest){
      //if(!this.$el.is(":animated")){
        this.$el.animate({scrollTop:this.opts.dest},this.opts.speed);
      //}
    }
  };
  scrollTo.prototype.go = function(){
    this.$el.scrollTop(this.opts.dest)
  };
  scrollTo.DEFAULTS = {
    dest:0,
    speed:800
  };
  return {
    scrollTo:scrollTo
  }
});