vue 利用原声input上传图片并预览并删除

<template>
  <div class="com-upload-img">
    <div class="img_group">
      <div v-if="allowAddImg" class="img_box">
        <input type="file" accept="image/*" multiple="multiple" @change="changeImg($event)">
        <div class="filter" />
      </div>
      <div v-for="(item,index) in imgArr" :key="index" class="img_box">
        <div class="img_show_box">
          <img :src="item" alt="">
          <i class="img_delete" @click="deleteImg(index)" />
          <!-- <i class="img_delete" @click="imgArr.splice(index,1)"></i> -->
        </div>
      </div>
    </div>
  </div>
</template>

<script>
export default {
  name: 'ComUpLoad',
  data() {
    return {
      imgData: '',
      imgArr: [],
      imgSrc: '',
      allowAddImg: true
    }
  },
  methods: {
    changeImg: function(e) {
      var _this = this
      var imgLimit = 1024
      var files = e.target.files
      var image = new Image()
      if (files.length > 0) {
        var dd = 0
        var timer = setInterval(function() {
          if (files.item(dd).type !== 'image/png' && files.item(dd).type !== 'image/jpeg' && files.item(dd).type !== 'image/gif') {
            return false
          }
          if (files.item(dd).size > imgLimit * 102400) {
            // to do sth
          } else {
            image.src = window.URL.createObjectURL(files.item(dd))
            image.onload = function() {
              // 默认按比例压缩
              var w = image.width
              var h = image.height
              var scale = w / h
              w = 200
              h = w / scale
              // 默认图片质量为0.7，quality值越小，所绘制出的图像越模糊
              var quality = 0.7
              // 生成canvas
              var canvas = document.createElement('canvas')
              var ctx = canvas.getContext('2d')
              // 创建属性节点
              var anw = document.createAttribute('width')
              anw.nodeValue = w
              var anh = document.createAttribute('height')
              anh.nodeValue = h
              canvas.setAttributeNode(anw)
              canvas.setAttributeNode(anh)
              ctx.drawImage(image, 0, 0, w, h)
              var ext = image.src.substring(image.src.lastIndexOf('.') + 1).toLowerCase()// 图片格式
              var base64 = canvas.toDataURL('image/' + ext, quality)
              // 回调函数返回base64的值
              if (_this.imgArr.length <= 4) {
                _this.imgArr.unshift('')
                _this.imgArr.splice(0, 1, base64)// 替换数组数据的方法，此处不能使用：this.imgArr[index] = url;
                if (_this.imgArr.length >= 5) {
                  _this.allowAddImg = false
                }
              }
            }
          }

          if (dd < files.length - 1) {
            dd++
          } else {
            clearInterval(timer)
          }
        }, 1000)
      }
    },
    deleteImg: function(index) {
      this.imgArr.splice(index, 1)
      if (this.imgArr.length < 5) {
        this.allowAddImg = true
      }
    }
  }
}
</script>