countUp.js实现数字滚动效果

本文实例为大家分享了countUp.js数字滚动效果展示的具体代码，供大家参考，具体内容如下

1. 概述

1.1 说明

在项目过程中，有时候需要动态的去展示一些数据的加载状态，如一个数字为10000，需要5秒时间滚动加载完成。此时使用countup.js就能够很方便的处理此类功能问题。

1.2 countup.js

countup.js是一个无依赖性、轻量级的javascript类，可用于快速创建动画，以更有趣的方式显示数字/数据。详见countup.js

1.3 countup.js使用

npm install countup  进行安装依赖

import CountUp from "countup"  在页面中引入

new CountUp(target, startVal, endVal, decimals, duration, options)

参数：

• 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

方法：

暂停/恢复      pauseResume
重置动画       reset
更新值           update(newVal)

2. 代码

2.1 源代码

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)
 }
};

2.1 代码示例

<!-- 数字滚动 -->
<template>
 <div id="numScroll" style="width: 200px;height: 200px;font-size: 30px;font-weight: bold;"></div>
</template>

<script>
 import CountUp from "countup"
 export default {
 name: "numberScroll.vue",
 mounted() {
  this.numberScroll()
 },
 methods: {
  numberScroll() {
  let count = new CountUp("numScroll", 0, 56565, 0, 5, {duration: 5, useEasing: false})
  if (!count.error) {
   count.start()
  } else {
   console.log(count.error)
  }
  }
 }
 }
</script>

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