//窗口显示才加载
var wraptop = $(".number-box").offset().top;
var istrue = true;
$(window).on("scroll",
  function() {
    var s = $(window).scrolltop();
    if (s > wraptop - 500 && istrue) {
      $(".timer").each(count);
      function count(a) {
        var b = $(this);
        a = $.extend({},
          a || {},
          b.data("counttooptions") || {});
        b.countto(a)
      };
      istrue = false;
    };
  })
//设置计数
$.fn.countto = function (options) {
  options = options || {};
  return $(this).each(function () {
    //当前元素的选项
    var settings = $.extend({}, $.fn.countto.defaults, {
      from:            $(this).data('from'),
      to:              $(this).data('to'),
      speed:           $(this).data('speed'),
      refreshinterval: $(this).data('refresh-interval'),
      decimals:        $(this).data('decimals')
    }, options);
    //更新值
    var loops = math.ceil(settings.speed / settings.refreshinterval),
      increment = (settings.to - settings.from) / loops;
    //更改应用和变量
    var self = this,
      $self = $(this),
      loopcount = 0,
      value = settings.from,
      data = $self.data('countto') || {};
    $self.data('countto', data);
    //如果有间断，找到并清除
    if (data.interval) {
      clearinterval(data.interval);
    };
    data.interval = setinterval(updatetimer, settings.refreshinterval);
    //初始化起始值
    render(value);
    function updatetimer() {
      value += increment;
      loopcount++;
      render(value);
      if (typeof(settings.onupdate) == 'function') {
        settings.onupdate.call(self, value);
      }
      if (loopcount >= loops) {
        //移出间隔
        $self.removedata('countto');
        clearinterval(data.interval);
        value = settings.to;
        if (typeof(settings.oncomplete) == 'function') {
          settings.oncomplete.call(self, value);
        }
      }
    }
    function render(value) {
      var formattedvalue = settings.formatter.call(self, value, settings);
      $self.html(formattedvalue);
    }
  });
};
$.fn.countto.defaults={
  from:0,               //数字开始的值
  to:0,                 //数字结束的值
  speed:1000,           //设置步长的时间
  refreshinterval:100,  //隔间值
  decimals:0,           //显示小位数
  formatter: formatter, //渲染之前格式化
  onupdate:null,        //每次更新前的回调方法
  oncomplete:null       //完成更新的回调方法
};
function formatter(value, settings){
  return value.tofixed(settings.decimals);
}
//自定义格式
$('#count-number').data('counttooptions',{
  formmatter:function(value, options){
    return value.tofixed(options.decimals).replace(/\b(?=(?:\d{3})+(?!\d))/g, ',');
  }
});
//定时器
$('.timer').each(count);
function count(options){
  var $this=$(this);
  options=$.extend({}, options||{}, $this.data('counttooptions')||{});
  $this.countto(options);
}