vue3实现数字滚动特效实例详解

目录

• 前言
• 思路
• 文件目录
• 使用示例
• 入口文件index.js
• main.js使用
• requestAnimationFrame.js思路
• 完整代码：
• CountTo.vue组件思路
• 总结

前言

vue3不支持vue-count-to插件，无法使用vue-count-to实现数字动效，数字自动分割，vue-count-to主要针对vue2使用，vue3按照会报错： TypeError: Cannot read properties of undefined (reading '_c') 的错误信息。这个时候我们只能自己封装一个CountTo组件实现数字动效。先来看效果图:

思路

使用Vue.component定义公共组件，使用window.requestAnimationFrame（首选，次选setTimeout）来循环数字动画，window.cancelAnimationFrame取消数字动画效果，封装一个requestAnimationFrame.js公共文件，CountTo.vue组件，入口导出文件index.js。

文件目录

使用示例

<CountTo
 :start="0" // 从数字多少开始
 :end="endCount" // 到数字多少结束
 :autoPlay="true" // 自动播放
 :duration="3000" // 过渡时间
 prefix="￥"   // 前缀符号
 suffix="rmb" // 后缀符号
 />

入口文件index.js

const UILib = {
  install(Vue) {
    Vue.component('CountTo', CountTo)
  }
}
export default UILib

main.js使用

import CountTo from './components/count-to/index';
app.use(CountTo)

requestAnimationFrame.js思路

• 先判断是不是浏览器还是其他环境
• 如果是浏览器判断浏览器内核类型
• 如果浏览器不支持requestAnimationFrame，cancelAnimationFrame方法，改写setTimeout定时器
• 导出两个方法 requestAnimationFrame, cancelAnimationFrame

各个浏览器前缀：let prefixes =  'webkit moz ms o';

判断是不是浏览器：let isServe = typeof window == 'undefined';

增加各个浏览器前缀：

let prefix;
let requestAnimationFrame;
let cancelAnimationFrame;
// 通过遍历各浏览器前缀，来得到requestAnimationFrame和cancelAnimationFrame在当前浏览器的实现形式
    for (let i = 0; i < prefixes.length; i++) {
        if (requestAnimationFrame && cancelAnimationFrame) { break }
        prefix = prefixes[i]
        requestAnimationFrame = requestAnimationFrame || window[prefix + 'RequestAnimationFrame']
        cancelAnimationFrame = cancelAnimationFrame || window[prefix + 'CancelAnimationFrame'] || window[prefix + 'CancelRequestAnimationFrame']
    }
  //不支持使用setTimeout方式替换：模拟60帧的效果
  // 如果当前浏览器不支持requestAnimationFrame和cancelAnimationFrame，则会退到setTimeout
    if (!requestAnimationFrame || !cancelAnimationFrame) {
        requestAnimationFrame = function (callback) {
            const currTime = new Date().getTime()
            // 为了使setTimteout的尽可能的接近每秒60帧的效果
            const timeToCall = Math.max(0, 16 - (currTime - lastTime))
            const id = window.setTimeout(() => {
                callback(currTime + timeToCall)
            }, timeToCall)
            lastTime = currTime + timeToCall
            return id
        }
        cancelAnimationFrame = function (id) {
            window.clearTimeout(id)
        }
    }

完整代码：

requestAnimationFrame.js

let lastTime = 0
const prefixes = 'webkit moz ms o'.split(' ') // 各浏览器前缀
let requestAnimationFrame
let cancelAnimationFrame
// 判断是否是服务器环境
const isServer = typeof window === 'undefined'
if (isServer) {
    requestAnimationFrame = function () {
        return
    }
    cancelAnimationFrame = function () {
        return
    }
} else {
    requestAnimationFrame = window.requestAnimationFrame
    cancelAnimationFrame = window.cancelAnimationFrame
    let prefix
    // 通过遍历各浏览器前缀，来得到requestAnimationFrame和cancelAnimationFrame在当前浏览器的实现形式
    for (let i = 0; i < prefixes.length; i++) {
        if (requestAnimationFrame && cancelAnimationFrame) { break }
        prefix = prefixes[i]
        requestAnimationFrame = requestAnimationFrame || window[prefix + 'RequestAnimationFrame']
        cancelAnimationFrame = cancelAnimationFrame || window[prefix + 'CancelAnimationFrame'] || window[prefix + 'CancelRequestAnimationFrame']
    }
    // 如果当前浏览器不支持requestAnimationFrame和cancelAnimationFrame，则会退到setTimeout
    if (!requestAnimationFrame || !cancelAnimationFrame) {
        requestAnimationFrame = function (callback) {
            const currTime = new Date().getTime()
            // 为了使setTimteout的尽可能的接近每秒60帧的效果
            const timeToCall = Math.max(0, 16 - (currTime - lastTime))
            const id = window.setTimeout(() => {
                callback(currTime + timeToCall)
            }, timeToCall)
            lastTime = currTime + timeToCall
            return id
        }
        cancelAnimationFrame = function (id) {
            window.clearTimeout(id)
        }
    }
}
export { requestAnimationFrame, cancelAnimationFrame }

CountTo.vue组件思路

首先引入requestAnimationFrame.js,使用requestAnimationFrame方法接受count函数，还需要格式化数字，进行正则表达式转换，返回我们想要的数据格式。

引入 import { requestAnimationFrame, cancelAnimationFrame } from './requestAnimationFrame.js'

需要接受的参数：

const props = defineProps({
  start: {
    type: Number,
    required: false,
    default: 0
  },
  end: {
    type: Number,
    required: false,
    default: 0
  },
  duration: {
    type: Number,
    required: false,
    default: 5000
  },
  autoPlay: {
    type: Boolean,
    required: false,
    default: true
  },
  decimals: {
    type: Number,
    required: false,
    default: 0,
    validator (value) {
      return value >= 0
    }
  },
  decimal: {
    type: String,
    required: false,
    default: '.'
  },
  separator: {
    type: String,
    required: false,
    default: ','
  },
  prefix: {
    type: String,
    required: false,
    default: ''
  },
  suffix: {
    type: String,
    required: false,
    default: ''
  },
  useEasing: {
    type: Boolean,
    required: false,
    default: true
  },
  easingFn: {
    type: Function,
    default(t, b, c, d) {
      return c * (-Math.pow(2, -10 * t / d) + 1) * 1024 / 1023 + b;
    }
  }
})

启动数字动效

const startCount = () => {
  state.localStart = props.start
  state.startTime = null
  state.localDuration = props.duration
  state.paused = false
  state.rAF = requestAnimationFrame(count)
}

核心函数，对数字进行转动

  if (!state.startTime) state.startTime = timestamp
  state.timestamp = timestamp
  const progress = timestamp - state.startTime
  state.remaining = state.localDuration - progress
  // 是否使用速度变化曲线
  if (props.useEasing) {
    if (stopCount.value) {
      state.printVal = state.localStart - props.easingFn(progress, 0, state.localStart - props.end, state.localDuration)
    } else {
      state.printVal = props.easingFn(progress, state.localStart, props.end - state.localStart, state.localDuration)
    }
  } else {
    if (stopCount.value) {
      state.printVal = state.localStart - ((state.localStart - props.end) * (progress / state.localDuration))
    } else {
      state.printVal = state.localStart + (props.end - state.localStart) * (progress / state.localDuration)
    }
  }
  if (stopCount.value) {
    state.printVal = state.printVal < props.end ? props.end : state.printVal
  } else {
    state.printVal = state.printVal > props.end ? props.end : state.printVal
  }
  state.displayValue = formatNumber(state.printVal)
  if (progress < state.localDuration) {
    state.rAF = requestAnimationFrame(count)
  } else {
    emits('callback')
  }
}
// 格式化数据，返回想要展示的数据格式
const formatNumber = (val) => {
  val = val.toFixed(props.default)
  val += ''
  const x = val.split('.')
  let x1 = x[0]
  const x2 = x.length > 1 ? props.decimal + x[1] : ''
  const rgx = /(\d+)(\d{3})/
  if (props.separator && !isNumber(props.separator)) {
    while (rgx.test(x1)) {
      x1 = x1.replace(rgx, '$1' + props.separator + '$2')
    }
  }
  return props.prefix + x1 + x2 + props.suffix
}

取消动效

// 组件销毁时取消动画
onUnmounted(() => {
  cancelAnimationFrame(state.rAF)
})

完整代码

<template>
  {{ state.displayValue }}
</template>
<script setup>  // vue3.2新的语法糖, 编写代码更加简洁高效
import { onMounted, onUnmounted, reactive } from "@vue/runtime-core";
import { watch, computed } from 'vue';
import { requestAnimationFrame, cancelAnimationFrame } from './requestAnimationFrame.js'
// 定义父组件传递的参数
const props = defineProps({
  start: {
    type: Number,
    required: false,
    default: 0
  },
  end: {
    type: Number,
    required: false,
    default: 0
  },
  duration: {
    type: Number,
    required: false,
    default: 5000
  },
  autoPlay: {
    type: Boolean,
    required: false,
    default: true
  },
  decimals: {
    type: Number,
    required: false,
    default: 0,
    validator (value) {
      return value >= 0
    }
  },
  decimal: {
    type: String,
    required: false,
    default: '.'
  },
  separator: {
    type: String,
    required: false,
    default: ','
  },
  prefix: {
    type: String,
    required: false,
    default: ''
  },
  suffix: {
    type: String,
    required: false,
    default: ''
  },
  useEasing: {
    type: Boolean,
    required: false,
    default: true
  },
  easingFn: {
    type: Function,
    default(t, b, c, d) {
      return c * (-Math.pow(2, -10 * t / d) + 1) * 1024 / 1023 + b;
    }
  }
})
const isNumber = (val) => {
  return !isNaN(parseFloat(val))
}
// 格式化数据，返回想要展示的数据格式
const formatNumber = (val) => {
  val = val.toFixed(props.default)
  val += ''
  const x = val.split('.')
  let x1 = x[0]
  const x2 = x.length > 1 ? props.decimal + x[1] : ''
  const rgx = /(\d+)(\d{3})/
  if (props.separator && !isNumber(props.separator)) {
    while (rgx.test(x1)) {
      x1 = x1.replace(rgx, '$1' + props.separator + '$2')
    }
  }
  return props.prefix + x1 + x2 + props.suffix
}
// 相当于vue2中的data中所定义的变量部分
const state = reactive({
  localStart: props.start,
  displayValue: formatNumber(props.start),
  printVal: null,
  paused: false,
  localDuration: props.duration,
  startTime: null,
  timestamp: null,
  remaining: null,
  rAF: null
})
// 定义一个计算属性，当开始数字大于结束数字时返回true
const stopCount = computed(() => {
  return props.start > props.end
})
// 定义父组件的自定义事件，子组件以触发父组件的自定义事件
const emits = defineEmits(['onMountedcallback', 'callback'])
const startCount = () => {
  state.localStart = props.start
  state.startTime = null
  state.localDuration = props.duration
  state.paused = false
  state.rAF = requestAnimationFrame(count)
}
watch(() => props.start, () => {
  if (props.autoPlay) {
    startCount()
  }
})
watch(() => props.end, () => {
  if (props.autoPlay) {
    startCount()
  }
})
// dom挂在完成后执行一些操作
onMounted(() => {
  if (props.autoPlay) {
    startCount()
  }
  emits('onMountedcallback')
})
// 暂停计数
const pause = () => {
  cancelAnimationFrame(state.rAF)
}
// 恢复计数
const resume = () => {
  state.startTime = null
  state.localDuration = +state.remaining
  state.localStart = +state.printVal
  requestAnimationFrame(count)
}
const pauseResume = () => {
  if (state.paused) {
    resume()
    state.paused = false
  } else {
    pause()
    state.paused = true
  }
}
const reset = () => {
  state.startTime = null
  cancelAnimationFrame(state.rAF)
  state.displayValue = formatNumber(props.start)
}
const count = (timestamp) => {
  if (!state.startTime) state.startTime = timestamp
  state.timestamp = timestamp
  const progress = timestamp - state.startTime
  state.remaining = state.localDuration - progress
  // 是否使用速度变化曲线
  if (props.useEasing) {
    if (stopCount.value) {
      state.printVal = state.localStart - props.easingFn(progress, 0, state.localStart - props.end, state.localDuration)
    } else {
      state.printVal = props.easingFn(progress, state.localStart, props.end - state.localStart, state.localDuration)
    }
  } else {
    if (stopCount.value) {
      state.printVal = state.localStart - ((state.localStart - props.end) * (progress / state.localDuration))
    } else {
      state.printVal = state.localStart + (props.end - state.localStart) * (progress / state.localDuration)
    }
  }
  if (stopCount.value) {
    state.printVal = state.printVal < props.end ? props.end : state.printVal
  } else {
    state.printVal = state.printVal > props.end ? props.end : state.printVal
  }
  state.displayValue = formatNumber(state.printVal)
  if (progress < state.localDuration) {
    state.rAF = requestAnimationFrame(count)
  } else {
    emits('callback')
  }
}
// 组件销毁时取消动画
onUnmounted(() => {
  cancelAnimationFrame(state.rAF)
})
</script>

总结

自己封装数字动态效果需要注意各个浏览器直接的差异，手动pollyfill，暴露出去的props参数需要有默认值，数据的格式化可以才有正则表达式的方式，组件的驱动必须是数据变化，根据数据来驱动页面渲染，防止页面出现卡顿，不要强行操作dom,引入的组件可以全局配置，后续组件可以服用

demo演示

后续的线上demo演示会放在 demo演示

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