/**
 * target: 目标元素的id  *必填
 * startval：开始的值(从哪个值开始)  *必填
 * endval：结束的值(滚动到哪个值结束)  *必填
 * decimals：小数位数，默认值为0  *可选
 * duration：动画持续时间，单位为秒，默认值为2  *可选
 * options：选项的可选对象  *可选
 * useeasing:true  --是否使用缓动动画，默认为缓动，可设置为false让其匀速
 * usegrouping:true --对数字进行分组，如12345，按三位一组变为类似12,345这样的
 * separator: ','  --分组时使用的分隔符默认是逗号
 * decimal: '.'  --小数点
 * prefix: ''  --添加前缀如12345，变为￥12345
 * suffix: ''  --添加后缀如12345 通过添加后缀变为12345$，12345元之类的
 */ 
var countup = function(target, startval, endval, decimals, duration, options) {
  var self = this;
  self.version = function() {
    return "1.9.2"
  };
  self.options = {
    useeasing: true,
    usegrouping: true,
    separator: ",",
    decimal: ".",
    easingfn: easeoutexpo,
    formattingfn: formatnumber,
    prefix: "",
    suffix: "",
    numerals: []
  };
  if (options && typeof options === "object") {
    for (var key in self.options) {
      if (options.hasownproperty(key) && options[key] !== null) {
        self.options[key] = options[key]
      }
    }
  }
  if (self.options.separator === "") {
    self.options.usegrouping = false
  } else {
    self.options.separator = "" + self.options.separator
  }
  var lasttime = 0;
  var vendors = ["webkit", "moz", "ms", "o"];
  for (var x = 0; x < vendors.length && !window.requestanimationframe; ++x) {
    window.requestanimationframe = window[vendors[x] + "requestanimationframe"];
    window.cancelanimationframe = window[vendors[x] + "cancelanimationframe"] || window[vendors[x] + "cancelrequestanimationframe"]
  }
  if (!window.requestanimationframe) {
    window.requestanimationframe = function(callback, element) {
      var currtime = new date().gettime();
      var timetocall = math.max(0, 16 - (currtime - lasttime));
      var id = window.settimeout(function() {
          callback(currtime + timetocall)
        },
        timetocall);
      lasttime = currtime + timetocall;
      return id
    }
  }
  if (!window.cancelanimationframe) {
    window.cancelanimationframe = function(id) {
      cleartimeout(id)
    }
  }

  function formatnumber(num) {
    num = num.tofixed(self.decimals);
    num += "";
    var x, x1, x2, x3, i, l;
    x = num.split(".");
    x1 = x[0];
    x2 = x.length > 1 ? self.options.decimal + x[1] : "";
    if (self.options.usegrouping) {
      x3 = "";
      for (i = 0, l = x1.length; i < l; ++i) {
        if (i !== 0 && ((i % 3) === 0)) {
          x3 = self.options.separator + x3
        }
        x3 = x1[l - i - 1] + x3
      }
      x1 = x3
    }
    if (self.options.numerals.length) {
      x1 = x1.replace(/[0-9]/g,
        function(w) {
          return self.options.numerals[+w]
        });
      x2 = x2.replace(/[0-9]/g,
        function(w) {
          return self.options.numerals[+w]
        })
    }
    return self.options.prefix + x1 + x2 + self.options.suffix
  }

  function easeoutexpo(t, b, c, d) {
    return c * (-math.pow(2, -10 * t / d) + 1) * 1024 / 1023 + b
  }

  function ensurenumber(n) {
    return (typeof n === "number" && !isnan(n))
  }
  self.initialize = function() {
    if (self.initialized) {
      return true
    }
    self.error = "";
    self.d = (typeof target === "string") ? document.getelementbyid(target) : target;
    if (!self.d) {
      self.error = "[countup] target is null or undefined";
      return false
    }
    self.startval = number(startval);
    self.endval = number(endval);
    if (ensurenumber(self.startval) && ensurenumber(self.endval)) {
      self.decimals = math.max(0, decimals || 0);
      self.dec = math.pow(10, self.decimals);
      self.duration = number(duration) * 1000 || 2000;
      self.countdown = (self.startval > self.endval);
      self.frameval = self.startval;
      self.initialized = true;
      return true
    } else {
      self.error = "[countup] startval (" + startval + ") or endval (" + endval + ") is not a number";
      return false
    }
  };
  self.printvalue = function(value) {
    var result = self.options.formattingfn(value);
    if (self.d.tagname === "input") {
      this.d.value = result
    } else {
      if (self.d.tagname === "text" || self.d.tagname === "tspan") {
        this.d.textcontent = result
      } else {
        this.d.innerhtml = result
      }
    }
  };
  self.count = function(timestamp) {
    if (!self.starttime) {
      self.starttime = timestamp
    }
    self.timestamp = timestamp;
    var progress = timestamp - self.starttime;
    self.remaining = self.duration - progress;
    if (self.options.useeasing) {
      if (self.countdown) {
        self.frameval = self.startval - self.options.easingfn(progress, 0, self.startval - self.endval, self.duration)
      } else {
        self.frameval = self.options.easingfn(progress, self.startval, self.endval - self.startval, self.duration)
      }
    } else {
      if (self.countdown) {
        self.frameval = self.startval - ((self.startval - self.endval) * (progress / self.duration))
      } else {
        self.frameval = self.startval + (self.endval - self.startval) * (progress / self.duration)
      }
    }
    if (self.countdown) {
      self.frameval = (self.frameval < self.endval) ? self.endval : self.frameval
    } else {
      self.frameval = (self.frameval > self.endval) ? self.endval : self.frameval
    }
    self.frameval = math.round(self.frameval * self.dec) / self.dec;
    self.printvalue(self.frameval);
    if (progress < self.duration) {
      self.raf = requestanimationframe(self.count)
    } else {
      if (self.callback) {
        self.callback()
      }
    }
  };
  self.start = function(callback) {
    if (!self.initialize()) {
      return
    }
    self.callback = callback;
    self.raf = requestanimationframe(self.count)
  };
  self.pauseresume = function() {
    if (!self.paused) {
      self.paused = true;
      cancelanimationframe(self.raf)
    } else {
      self.paused = false;
      delete self.starttime;
      self.duration = self.remaining;
      self.startval = self.frameval;
      requestanimationframe(self.count)
    }
  };
  self.reset = function() {
    self.paused = false;
    delete self.starttime;
    self.initialized = false;
    if (self.initialize()) {
      cancelanimationframe(self.raf);
      self.printvalue(self.startval)
    }
  };
  self.update = function(newendval) {
    if (!self.initialize()) {
      return
    }
    newendval = number(newendval);
    if (!ensurenumber(newendval)) {
      self.error = "[countup] update() - new endval is not a number: " + newendval;
      return
    }
    self.error = "";
    if (newendval === self.frameval) {
      return
    }
    cancelanimationframe(self.raf);
    self.paused = false;
    delete self.starttime;
    self.startval = self.frameval;
    self.endval = newendval;
    self.countdown = (self.startval > self.endval);
    self.raf = requestanimationframe(self.count)
  };
  if (self.initialize()) {
    self.printvalue(self.startval)
  }
};