方法一

    downloadIamge(url, name) {
      var _this = this
      var canvas = document.createElement('canvas')
      var img = document.createElement('img')
      // 下载有时候会失效 通过改变url链接进行递归
      img.onerror = function() {
        var timeStamp = +new Date()
        _this.downloadIamge(url + '?' + timeStamp, name)
      }
      img.onload = function(e) {
        canvas.width = img.width
        canvas.height = img.height
        var context = canvas.getContext('2d')
        context.drawImage(img, 0, 0, img.width, img.height)
        canvas.getContext('2d').drawImage(img, 0, 0, img.width, img.height)
        canvas.toBlob((blob) => {
          const link = document.createElement('a')
          link.href = window.URL.createObjectURL(blob)
          link.download = name
          link.click()
        }, 'image/png')
      }
      img.setAttribute('crossOrigin', 'Anonymous')
      img.src = url
    }

方法二(下载不稳定还是要加入方法一中的img.onerror)

    download(imgsrc, name) { // 下载图片地址和图片名
      var image = new Image()
      // 解决跨域 Canvas 污染问题
      image.setAttribute('crossOrigin', 'anonymous')
      image.onload = function() {
        var canvas = document.createElement('canvas')
        canvas.width = image.width
        canvas.height = image.height
        var context = canvas.getContext('2d')
        context.drawImage(image, 0, 0, image.width, image.height)
        var url = canvas.toDataURL('image/png') // 得到图片的base64编码数据
        var a = document.createElement('a') // 生成一个a元素
        var event = new MouseEvent('click') // 创建一个单击事件
        a.download = name || 'photo' // 设置图片名称
        a.href = url // 将生成的URL设置为a.href属性
        a.dispatchEvent(event) // 触发a的单击事件
      }
      image.src = imgsrc
    },