countup.js 的简单使用

countup.js

countup.js 是一个轻量级，无依赖的JavaScript类，通过简单的设置就可以达到数字滚动的效果
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官网

源码

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)}};

使用

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  
  <script src="./js/countUp.js"></script>
</head>
<body>
  
  <div id="num1">23</div>
  <div class="btn" style="background-color: brown; color: #fff;width: 100px;height: 30px;line-height: 30px;text-align: center;">这是个按钮</div>
</body>
<script>
  var options={
      useEasing: true,  // 过渡动画效果，默认ture
      useGrouping: true,  // 千分位效果，例：1000->1,000。默认true
      separator: ',',   // 使用千分位时分割符号
      decimal: '.',   // 小数位分割符号
      prefix: '',    // 前置符号
      suffix: ''    // 后置符号，可汉字
  }
  // target,startVal,endVal,decimals,duration,options
            // dom节点, 初始值,  结束值, 小数位数, 过渡几秒 , 初始参数
  var num1 = new CountUp('num1', 99, 100, 0, 20,options),
      num2 = new CountUp('num2', 0, 200, 0, 2,options)

  function start(){
      // 开始
      num1.start()
  }
  function pause(){
      // 暂停或继续
      num1.pauseResume()
  }
  function reset(){
      // 重置初始值
      num1.reset()
  }
  function updata(){
      // 重新赋值
      num1.update(888)
  }

//滚动到当前元素执行start()
  let numDiv = document.querySelector('#num1')
  document.addEventListener("scroll", function (e) {
    // console.log(document.documentElement.scrollTop, numDiv.offsetTop)
    // console.log(window.innerHeight)
    let a = document.documentElement.scrollTop + window.innerHeight - numDiv.offsetTop
    if(a > 0){
      start()
    }
  })

  $('.btn').click(function(){
    start()
    reset()
  })
</script>
</html>